Data Sheet


x Broadband Wireless Access (including 802.16 and 802.20. WiMax) ... Small/Large -signal data measured in a fully de-embedded test fixture form TA = 2...

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AMMP-6650 DC – 30 GHz Variable Attenuator

Data Sheet

Description

Features

The AMMP-6650 is a voltage controlled variable attenuator in a surface mount package, designed to operate from DC to 30 GHz. It is fabricated using Avago Technologies enhancement mode pHEMT MMIC process and requires only positive voltage control. The distributed topology of the AMMP-6650 facilitates broadband operation by absorbing parasitic effects of its series and shunt FETs. An on-chip DC reference circuit may be used to maintain optimum VSWR for any attenuation setting or to provide more linear attenuation versus voltage response.

x 5 x 5 mm Surface Mount Package x Wide Frequency Range DC - 30 GHz x Attenuation Range 20dB x Single Positive Bias Supply x Unconditionally Stable

Applications x Microwave Radio Systems x Satellite VSAT, DBS Up / Down Link

Package Diagram

x LMDS & Pt – Pt mmW Long Haul

DCin

NC

DCout

1

2

3

x Broadband Wireless Access (including 802.16 and 802.20 WiMax) x WLL and MMDS loops

Functional Block Diagram RFin

8

4

7

6

5

V1

NC

V2

RFout

DCin

NC

DCout

1

2

3

DC reference circuit RFin

8

4

variable attenuator

7 V1

6

5

NC

V2

RFout

Pin 1 2 3 4 5 6 7 8

Function DC in NC DC out RF out V2 NC V1 RF in

Top View Note : Package base : GND

RoHS-Exemption Attention: Observe precautions for handling electrostatic sensitive devices. ESD Machine Model = 80 V ESD Human Body Model = 400 V Refer to Avago Application Note A004R: Electrostatic Discharge, Damage and Control. Please refer to hazardous substances table on page 9.

Note: MSL Rating = Level 2A

Electrical Specifications 1. Small/Large -signal data measured in a fully de-embedded test fixture form TA = 25°C. 2. Data obtained from on-wafer measurement 3. This final package part performance is verified by a functional test correlated to actual performance at one or more frequencies. 4. Specifications are derived from measurements in a 50 Ω test environment. Aspects of the amplifier performance may be improved over a more narrow bandwidth by application of additional conjugate, linearity, or low noise (Гopt) matching.

Table 1. RF Electrical Characteristics [1,2] Symbol

Parameters and Test Conditions

Units

Freq. [GHz]

Minimum Attenuation (Reference State)

|S21| V1 = 1.5 V V2 = 0.0 V

dB

Maximum Attenuation

dB |S21| V1 = 0.0 V V2 = 1.25 V

Minimum

Typical

Maximum

2

0.9

1.5

10

2.0

2.5

20

0.9

2.5

30

2.1

3.0

2

23

26.6

10

23

28.0

20

23

30.0

30

23

35.6

Return Loss (In/Out) at Reference State

V1=1.5 V, V2=0.0 V

dB

<30

10

Return Loss (In/Out) at Max. Attenuation

V1=0.0 V, V2=1.25 V

dB

<30

10

Table 2. Recommended Operating Range 1. Ambient operational temperature TA = 25°C unless otherwise noted. 2. Data obtained from on-wafer measurement Parameter

Min.

Typical

Max.

Unit

Test Condition

V1 Control Current (Min Attenuation), Ic_V1_ref

1.93

2.0

mA

Vse=1.2V, Vsh=0

V2 Control Current (Min Attenuation), Ic_V2_ref

0.8

2.5

uA

Vse=0V, Vsh=1.2V

V1 Control Current (Max Attenuation), Ic_V1_max

1.1

2.5

uA

Vse=0V, Vsh=1.2V

V2 Control Current (Max Attenuation), Ic_V2_max

1.41

1.5

mA

Vse=1.2V, Vsh=0

Table 3. Absolute Minimum and Maximum Ratings [1] Parameter

Min.

Max.

Unit

Voltage to Control VSWR, V1

0

1.6

V

Voltage to Control Attenuation, V2

0

1.6

V

RF Input Power, Pin

17

dBm

Operating Channel Temperature, Tch

+150

dB

+150

°C

300

°C

Storage Temperature, Tstg Maximum Assembly Temperature, Tmax

-65

Comments

60 second maximum

Notes: 1. Operation in excess of any one of these conditions may result in permanent damage to this device. The absolute maximum ratings for V1, V2 and Pin were determined at an ambient temperature of 25°C unless noted otherwise..

2

Typical Performance (TA = 25°C, Zin = Zout = 50 :) 0

Min+2dB Min+4dB

20

Min+8dB

30

Min+12dB Min+16dB

40

Min+20dB Max

50 0

5

10

15 20 Frequency (GHz)

25

Min Max

-40

0

5

10

15 20 Frequency (GHz)

25

30

Figure 2. Input Return Loss vs Frequency

0

30

-10

25 20 IIP3 (dBm)

-20 -30 -40

Min Max

15 10 5 0

0

5

10

15 20 Frequency (GHz)

25

30

0

10

20

30

20

30

Attenuation (dB)

Figure 3. Output Return Loss vs Frequency

Figure 4. IIP3 vs Attenuation at 2 GHz (note 2)

30

30

25

25

20

20 IIP3 (dBm)

IIP3 (dBm)

-30

-50

-50

15 10

15 10 5

5

0

0 0

10

20 Attenuation (dB)

Figure 5. IIP3 vs Attenuation at 12 GHz (note 2)

3

-20

30

Figure 1. Attenuation vs Frequency

Output Return Loss (dB)

-10 Input Return Loss (dB)

10 Attenuation (dB)

0

Min

30

0

10 Attenuation (dB)

Figure 6. IIP3 vs Attenuation at 22 GHz (note 2)

0

0 Min

5

Min+4dB Min+8dB

15

Min+12dB 20

Min+16dB

Attenuation (dB)

Attenuation (dB)

10

Min+20dB

25

Max

30 -10

-5

0 5 Input Power (dBm)

Min+4dB

15

Min+8dB

20

Min+12dB

25

Min+16dB

30

Min+20dB Max -10

10

-5

0 5 Input Power (dBm)

10

Figure 8. Attenuation vs Input Power at 12 GHz

0

0 Min

5

Min+2dB

10

Min+4dB 15

Min+8dB

20

Min+12dB

25

Min+16dB

30

Min+20dB

-10

-5

0 5 Input Power (dBm)

Min+2dB

10

Min+4dB 15

Min+8dB

20

Min+12dB

25

Min+16dB Min+20dB

30

Max

35

Min

5 Attenuation (dB)

Attenuation (dB)

Min+2dB

10

35

Figure 7. Attenuation vs Input Power at 2 GHz

Max

35 -10

10

Figure 9. Attenuation vs Input Power at 22 GHz

-5

0 5 Input Power (dBm)

10

Figure 10. Attenuation vs Input Power at 32 GHz

0

0 2

-40C 25C 85C

10 Attenuation (dB)

Attenuation (dB)

Min

5

Min+2dB

4 6 -40C 25C 85C

8

20

30 40

10 0

5

10 15 20 Frequency (GHz)

Figure 11. Attenuation vs Frequency (Min Attenuation)

25

30

0

5

10 15 Frequency (GHz)

20

Figure 12. Attenuation vs Frequency (Max Attenuation)

Notes: 1. All tests done on an AMMP-6650 mounted on a PCB equipped with RF connectors and an op-amp driver shown in Figure 14. 2. IIP3 measured with two input signals with frequency difference of 10 MHz, each input signal at -10 dBm 3. All attenuation settings were done at 2GHz utilizing the AMMP-6650 DC Reference circuit. VREF was set to 0.1 volt.

4

25

30

AMMP-6650 Typical Scattering Parameters at Minimum Attenuation (Tc = 25°C, Zo = 50ohm, V1 = 1.5V, V2 = 0V) Freq GHz

dB

S11 Mag

Phase

dB

S21 Mag

Phase

dB

S12 Mag

Phase

dB

S22 Mag

Phase

0.5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

-26.02 -26.02 -22.73 -20.09 -18.34 -16.95 -16.03 -15.34 -14.8 -14.7 -14.47 -14.75 -14.85 -15.39 -15.92 -16.83 -17.86 -19.33 -21.11 -23.35 -27.33 -32.77 -31.7 -25.68 -21.62 -18.34 -16.48 -14.99 -14.33 -14.24 -14.47 -14.52 -14.99 -16.03 -17.72 -20.09 -22.5 -23.48 -21.41 -18.56 -16.36 -14.56 -13.11 -12.01 -11.28 -10.81 -10.57 -10.6 -10.78 -11.28

0.05 0.05 0.07 0.1 0.12 0.14 0.16 0.17 0.18 0.18 0.19 0.18 0.18 0.17 0.16 0.14 0.13 0.11 0.09 0.07 0.04 0.02 0.03 0.05 0.08 0.12 0.15 0.18 0.19 0.19 0.19 0.19 0.18 0.16 0.13 0.1 0.08 0.07 0.09 0.12 0.15 0.19 0.22 0.25 0.27 0.29 0.3 0.3 0.29 0.27

-39.1 -66.7 -93.5 -108 -120.3 -131.5 -140.9 -149.7 -157.5 -165.3 -172.9 -180 172.5 165.6 158.2 151 143.5 135.1 127.3 116.3 99.3 59.4 -19.1 -54 -71.5 -85.7 -100.6 -114.3 -127.7 -137.9 -147.1 -155.5 -164.2 -171.7 -177.3 -178 -166.3 -143.6 -122.9 -116.9 -118.7 -123.8 -130.9 -139.4 -148.9 -158.8 -169.5 -179.7 170.4 162.1

-1.13 -1.1 -1.13 -1.24 -1.31 -1.36 -1.42 -1.46 -1.52 -1.55 -1.62 -1.64 -1.68 -1.7 -1.73 -1.76 -1.78 -1.8 -1.81 -1.83 -1.86 -1.92 -2 -2.12 -2.23 -2.35 -2.38 -2.45 -2.5 -2.58 -2.65 -2.7 -2.73 -2.78 -2.83 -2.83 -2.95 -2.96 -3.01 -3.12 -3.25 -3.43 -3.69 -4.01 -4.34 -4.78 -5.26 -5.66 -6.14 -6.76

0.88 0.88 0.88 0.87 0.86 0.86 0.85 0.85 0.84 0.84 0.83 0.83 0.82 0.82 0.82 0.82 0.82 0.81 0.81 0.81 0.81 0.8 0.79 0.78 0.77 0.76 0.76 0.75 0.75 0.74 0.74 0.73 0.73 0.73 0.72 0.72 0.71 0.71 0.71 0.7 0.69 0.67 0.65 0.63 0.61 0.58 0.55 0.52 0.49 0.46

-5.8 -10.3 -19.2 -28.1 -36.9 -45.5 -54.2 -62.7 -71.3 -79.8 -88.4 -96.8 -105.4 -114.1 -122.8 -131.5 -140.3 -149.3 -158.4 -167.7 -176.9 173.5 163.9 154.2 144.6 135.4 126.8 118.8 110.1 101.1 91.5 82.3 73.2 63.3 53.1 42.8 32 21 9.9 -1.5 -13 -24.9 -36.8 -48.7 -60.5 -72.7 -84.2 -95.7 -107.7 -119.1

-1.15 -1.18 -1.23 -1.34 -1.43 -1.47 -1.55 -1.6 -1.65 -1.7 -1.74 -1.79 -1.82 -1.84 -1.85 -1.87 -1.88 -1.89 -1.92 -1.94 -1.96 -2.03 -2.09 -2.21 -2.35 -2.45 -2.5 -2.56 -2.59 -2.64 -2.69 -2.72 -2.77 -2.83 -2.88 -2.93 -2.96 -3.01 -3.09 -3.2 -3.31 -3.49 -3.76 -4.08 -4.42 -4.82 -5.29 -5.71 -6.23 -6.8

0.88 0.87 0.87 0.86 0.85 0.84 0.84 0.83 0.83 0.82 0.82 0.81 0.81 0.81 0.81 0.81 0.81 0.8 0.8 0.8 0.8 0.79 0.79 0.78 0.76 0.75 0.75 0.75 0.74 0.74 0.73 0.73 0.73 0.72 0.72 0.71 0.71 0.71 0.7 0.69 0.68 0.67 0.65 0.63 0.6 0.57 0.54 0.52 0.49 0.46

-5.8 -10.3 -19.2 -28.1 -36.9 -45.5 -54 -62.5 -71 -79.5 -88 -96.5 -105.1 -113.7 -122.4 -131.2 -139.9 -148.9 -158 -167.1 -176.5 174 164.4 154.7 145.2 136 127.3 119.2 110.6 101.6 91.9 82.8 73.8 63.9 53.7 43.3 32.7 21.8 10.6 -0.7 -12.2 -24.1 -36.1 -48.2 -59.7 -71.9 -83.5 -95.1 -107 -118.5

-26.2 -25.51 -22.62 -20.18 -18.56 -17.33 -16.36 -15.76 -15.24 -15.04 -14.94 -14.99 -15.34 -15.81 -16.42 -17.33 -18.64 -20.18 -22.16 -24.88 -28.64 -35.39 -37.72 -29.37 -24.44 -20.92 -18.49 -16.77 -15.86 -15.49 -15.65 -15.76 -16.14 -17.2 -18.86 -20.92 -23.48 -24.01 -21.62 -18.56 -16.31 -14.33 -12.69 -11.5 -10.66 -9.95 -9.47 -9.22 -9.14 -9

0.05 0.05 0.07 0.1 0.12 0.14 0.15 0.16 0.17 0.18 0.18 0.18 0.17 0.16 0.15 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0.01 0.03 0.06 0.09 0.12 0.15 0.16 0.17 0.17 0.16 0.16 0.14 0.11 0.09 0.07 0.06 0.08 0.12 0.15 0.19 0.23 0.27 0.29 0.32 0.34 0.35 0.35 0.36

-39.2 -60.2 -85.5 -102.1 -115.4 -127.6 -137.4 -146.5 -155 -163.3 -171.8 179.9 172.3 164.3 156.6 148.6 141.1 134 125.4 118.4 107.6 81.1 -23.8 -61.8 -73.2 -85.7 -98.5 -111 -123.6 -134.6 -144.9 -151.7 -160.2 -168.8 -174.7 -173.1 -162.3 -137.3 -117.7 -113.5 -115.9 -122 -130.4 -139.5 -149.8 -160.7 -171.9 176.6 165 152.8

Notes: AMMP-6650 mounted on a PCB equipped with RF connectors and an op-amp driver shown in Figure 14.

5

AMMP-6650 Typical Scattering Parameters at Maximum Attenuation (Measured on-wafer, Tc = 25°C, Zo = 50ohm, V1 = 0V, V2 = 1.25V) Freq GHz

dB

S11 Mag

Phase

dB

S21 Mag

Phase

dB

S12 Mag

Phase

dB

S22 Mag

Phase

0.5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

-22.85 -22.5 -21.94 -20.82 -19.83 -19.02 -18.2 -17.46 -16.77 -16.36 -15.86 -15.49 -15.29 -15.19 -14.99 -15.04 -15.19 -15.34 -15.44 -15.7 -15.97 -16.14 -16.48 -16.95 -17.52 -18.06 -18.64 -19.33 -19.66 -20.54 -21.62 -22.73 -24.01 -25.51 -26.94 -27.54 -27.13 -25.85 -23.88 -22.16 -20.35 -19.25 -17.92 -17.14 -16.42 -15.76 -15.04 -14.29 -13.47 -12.04

0.07 0.08 0.08 0.09 0.1 0.11 0.12 0.13 0.15 0.15 0.16 0.17 0.17 0.17 0.18 0.18 0.17 0.17 0.17 0.16 0.16 0.16 0.15 0.14 0.13 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.05 0.04 0.04 0.05 0.06 0.08 0.1 0.11 0.13 0.14 0.15 0.16 0.18 0.19 0.21 0.25

-12.3 -21.6 -38.5 -53.4 -67 -78.6 -89 -98.9 -107 -114.6 -121.5 -127.9 -134.6 -140.7 -146.6 -151.7 -156.8 -162 -166.1 -170.4 -174.7 -178.9 176.4 170.7 166.5 164.2 159.6 154.9 149.9 144.5 135.2 126.4 118.1 103.6 81.6 58 33.7 12.4 -1.6 -16 -25.2 -32.1 -40.3 -46.9 -52.7 -57 -58 -58.8 -62.3 -67.5

-24.44 -24.44 -24.58 -24.44 -24.44 -24.29 -24.15 -24.01 -23.88 -23.74 -23.48 -23.35 -23.22 -23.1 -23.1 -22.97 -22.85 -22.97 -23.1 -23.48 -24.01 -24.44 -24.88 -25.35 -25.85 -26.2 -26.74 -27.33 -27.96 -28.18 -28.4 -28.87 -28.87 -29.12 -29.63 -29.9 -30.17 -30.75 -31.06 -31.7 -32.04 -32.4 -33.15 -33.98 -34.42 -34.89 -35.92 -36.48 -37.72 -38.42

0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.06 0.06 0.06 0.05 0.05 0.05 0.05 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.01

-3.8 -6.7 -12.6 -18.5 -24.6 -30.8 -37.1 -44 -51.1 -58.5 -66.2 -74.1 -82.4 -91 -100 -109.5 -119.4 -130.1 -141.6 -153.4 -164.8 -174.2 178.2 172.3 167.1 164.2 159.2 154 146.1 137.2 127.3 120.3 112.8 104 95.5 86.6 77.8 69.3 61.3 53.2 45.6 36.2 27.5 18.7 10.3 -0.1 -10 -19.6 -29.1 -41.4

-24.58 -24.58 -24.58 -24.44 -24.44 -24.29 -24.15 -24.01 -23.88 -23.61 -23.48 -23.35 -23.22 -23.1 -22.97 -22.97 -22.85 -22.85 -23.1 -23.48 -23.88 -24.44 -24.88 -25.19 -25.68 -26.2 -27.13 -27.54 -27.74 -28.18 -28.4 -28.87 -28.87 -29.12 -29.37 -29.9 -30.17 -30.75 -31.37 -31.7 -32.04 -32.77 -33.15 -33.56 -34.42 -35.39 -35.92 -36.48 -37.72 -37.72

0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.06 0.06 0.06 0.06 0.05 0.05 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.01

-3.7 -6.7 -12.7 -18.5 -24.7 -30.8 -37.2 -43.8 -50.9 -58.5 -66.1 -74.1 -82.3 -90.9 -100 -109.6 -119.4 -130.1 -141.7 -153.2 -164.8 -174.2 178.2 172.3 167 163.9 159 153.4 145.7 137.1 126.5 120.3 112.6 103.2 95.1 86.3 77 70.4 59.1 53.8 43.4 34.8 27.4 17.2 11.9 -2.9 -7.6 -18.6 -28.8 -37.8

-22.62 -22.5 -21.94 -21.01 -20.18 -19.25 -18.42 -17.65 -17.02 -16.48 -16.08 -15.76 -15.49 -15.34 -15.29 -15.24 -15.39 -15.55 -15.76 -15.92 -15.86 -15.92 -16.03 -16.14 -16.48 -16.83 -17.14 -17.59 -17.92 -18.56 -19.17 -20 -20.63 -21.31 -21.62 -21.83 -21.94 -21.62 -21.01 -20.45 -19.66 -18.79 -18.2 -17.86 -17.27 -16.89 -16.65 -15.92 -14.7 -13.56

0.07 0.08 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.16 0.17 0.17 0.17 0.17 0.17 0.17 0.16 0.16 0.16 0.16 0.16 0.16 0.15 0.14 0.14 0.13 0.13 0.12 0.11 0.1 0.09 0.09 0.08 0.08 0.08 0.08 0.09 0.1 0.1 0.12 0.12 0.13 0.14 0.14 0.15 0.16 0.18 0.21

-12.7 -21.4 -38 -53.6 -66.8 -78.9 -89.1 -98.2 -107 -115 -122.5 -129.7 -136.5 -142.7 -149.2 -154.9 -160.4 -165.3 -169.3 -172.9 -176.5 178.7 173.4 167.4 161.9 156.1 149.9 143.3 136.2 128.3 118.7 109.2 99.5 86.3 71.8 57.5 41.4 26.2 12.2 0.4 -11.7 -21.6 -29.8 -38 -44.2 -47.7 -49 -49.9 -51 -54.4

Notes:

AMMP-6650 mounted on a PCB equipped with RF connectors and an op-amp driver shown in Figure 14.

6

Biasing considerations DCin 1

NC

VREF RS 500 NC

DCout

2

3

DC reference circuit RFin

8

4

variable attenuator

7

6

5

V1

NC

V2

RFout

Pin 1 2 3 4 5 6 7 8

DCin

Function DC in NC DC out RF out V2 NC V1 RF in

DCout

RFin

RL (500)

RFout

V1

V2 NC

OP AMP 1 A + B _

OP AMP 2 + C _ D

VCONTROL R1 (10K)

Note : Package base : GND

500 RREF (620)

Figure 13. Bias voltage connections

Figure 14. AMMP-6650 and the op-amp driver circuit

Attenuation is controlled by applying voltage to pin V1 (Pin 7) and pin V2 (Pin5), as shown in Figure 13.

If optimum VSWR is all that is required, OP AMP 2 may be eliminated however, RL must remain connected to the DCout pad of the AMMP-6650 and the control voltage can be applied directly to V2.

Top View

For the minimum attenuation, V1 is set to 1.5 V and V2 is set to 0 V. The 1.5 V applied to the V1 pin biases the series FETs to a full “on” state, while the 0 V applied to the V2 pin keeps the shunt FETs in an “off” or “open” state; thus creating the lumped element 50 Ω transmission line effect. The V2 voltage swing from 0 V to 1.25 V increases the level of attenuation. The V1 voltage swing from 1.5 V to 0 V effectively optimizes the input and output match at higher attenuation levels. The AMMP-6650 can be driven by two complementary voltage ramps placed on V1 and V2. Careful adjustments of the two control lines over a relatively small voltage ranges are required to set the attenuation and optimize VSWR. The on-chip DC reference circuit can be used to optimize VSWR for any attenuation setting, improve voltage versus attenuation linearity and range, and provide temperature compensation. The on-chip DC reference circuit is a non-distributed “T” attenuator designed to operate in a 500 : system and track the control voltage versus attenuation characteristics of the RF attenuator. A simplified schematic of the AMMP-6650 together with an op-amp driver that utilizes the DC reference circuit is shown in Figure 14. OP AMP 1 insures that the attenuator maintains a good input and output match to 50 :, while OP AMP 2 increases the usable control voltage range versus using only direct voltage ramps for V1 and V2 and improves over temperature operation.

7

R2 (100) C1

CAUTION: Low voltage op-amps must be used so as not to exceed the maximum limit of V1 and V2 control voltages. As shown, a voltage reference (VREF) is fed to the reference circuit DCin pad via a 500 : resistor, creating a 500 : source. The reference circuit termination RL, is connected to the DCout pad and ideally is also equal to 500 :. This voltage is controlled in parallel with the RF attenuator. The chosen value of VREF must be low enough to avoid modifying the FET biasing and lower than the turn-on voltage of the ESD protection diode but high enough such that the attenuated voltage at OP AMP 2 is usable compared to input offsets etc. The optimum value for the positive reference voltage is approximately 0.1 to 0.4 V. At equilibrium, the voltages at nodes A and B of the OP AMP 1 must be equal which implies that the input impedance to the DC reference circuit is equal to RREF. When V2 is changed to a lower value, the voltage at node A becomes greater than that of node B. This voltage difference causes the output voltage of op OP AMP 1 to move toward its positive rail until equilibrium is once again established. When V2 is changed to a higher value the voltage at node A becomes less than that of node B and the output voltage of OP AMP 1 will swing toward its negative rail until equilibrium is reached. If the reference circuit precisely tracks the RF circuit, the voltage output of OP AMP 1 at equilibrium insures that the RF circuit is matched to 50 :.

If attenuation linearity is required, OP AMP 2 is included as shown in Figure 14 and a positive control voltage is applied to VCONTROL. At equilibrium, voltages at nodes C and D are equal. When VCONTROL is changed, the output of OP AMP 2 adjusts to a value that forces the voltage at node C to equal the voltage at node D. Therefore, the output voltage of the DC reference circuit is proportional to VCONTROL. The input voltage to the reference circuit is being held constant and the log(VCONTROL) is proportional to the reference circuit attenuation 20log(DCout/DCin).

The voltage divider formed by R1 and R2 can be used to adjust the sensitivity of the attenuator versus control voltage. For the driver circuit shown in Figure 14, maximum attenuation is always achieved by setting VCONTROL equal to 0 V. Minimum attenuation is achieved when

If the FET parameters of the DC reference circuit track the FET parameters of the RF circuit, the voltage output of the RF circuit is also proportional to the control voltage. This translates to a linear relationship between the attenuation (in dB) and the log(VCONTROL).

§ R1 Vcontrol ≈ ¨1 + R2 ©

Due to the difference in layout structures, the reference circuit does not track the RF circuit precisely. RL and RREF can be adjusted in order to compensate for these differences. Optimum values of RL and RREF have been found to be between 500 : and 650 :. For maximum dynamic range on the attenuation control circuit, RL should be less than RREF by an amount equal to the “ON resistance” of the reference circuit series FETs. The “ON resistance” of the series FETs is about 95 : total. Therefore, the relationship between RL and RREF is as follows: RREF = RL + 95 :

8

or

§ ¨ ©

x DCout

Therefore, an increase in the resistor ratio R1/R2 increases the value of the control voltage required to produce minimum attenuation. LMV932 (National Semiconductor) was used in the control circuit that produced the results shown in Figure 15; however, any low noise, low offset voltage op amp should produce similar results. LMV932’s low supply voltage of 1.8 volts, limits the possibility of exceeding the 1.5 volt absolute maximum of the AMMC-6650 V1 and V2 control line inputs.

Attenuation (dB)

Another way to improve performance of the attenuator driver circuit is to adjust RL and RREF . If the reference circuit precisely tracked the RF circuit and the ON resistance of the FETs was zero ohms, then RL and RREF would be exactly 500 :.

§ ¨ ©

OP AMP 2 provides temperature compensation by adjusting V2 in such a way as to keep voltage at point C equal to that point D. If the attenuation changes over temperature, voltage at point C tries to change, but is corrected by OP AMP 2.

§ ¨ ©

Two RF attenuation vs voltage curves corresponding to different values of VREF are shown in Figure 15. These curves were obtained by using the driver circuit shown in Figure 14 and the VREF values 0.1 V and 0.4 V. Values for RL, R1 and R2 were 500 :, 10 k: and 100 : respectively. Control voltage ranged from 4.5 V to 0 V. Because the FETs in the DC circuit are not identical to those in the RF circuit, the DC circuit does not exactly track the RF circuit. This results in attenuation vs. voltage curves that are not exactly linear.

§ RL § R1 + R2 Vcontrol ≈ ¨ x¨ x Vref 500 :+ RL R2 © ©

0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 0.01

Vref=0.1V Vref=0.2V

0.1 1 Control Voltage (Vin)

Figure 15. Attenuation vs. Control Voltage @ 15 GHz

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Package Dimension, PCB Layout and Tape and Reel information Please refer to Avago Technologies Application Note 5520, AMxP-xxxx production Assembly Process (Land Pattern A).

Ordering Information Part Number

Devices Per Container

Container

AMMP-6650-BLKG

10

Antistatic bag

AMMP-6650-TR1G

100

7” Reel

AMMP-6650-TR2G

500

7” Reel

Names and Contents of the Toxic and Hazardous Substances or Elements in the Products

Part Name

Toxic and Hazardous Substances or Elements Lead (Pb) (Pb)

Mercury (Hg) Hg

Cadmium (Cd) Cd

Hexavalent (Cr(VI)) Cr(VI)

Polybrominated biphenyl (PBB) PBB

100pF capacitor : indicates that the content of the toxic and hazardous substance in all the homogeneous materials of the part is below the concentration limit requirement as described in SJ/T 11363-2006. : indicates that the content of the toxic and hazardous substance in at least one homogeneous material of the part exceeds the concentration limit requirement as described in SJ/T 11363-2006. (The enterprise may further explain the technical reasons for the “x” indicated portion in the table in accordance with the actual situations.)

SJ/T 11363-2006 SJ/T 11363-2006 “×” Note: EU RoHS compliant under exemption clause of “lead in electronic ceramic parts (e.g. piezoelectronic devices)”

For product information and a complete list of distributors, please go to our web site:

www.avagotech.com

Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies in the United States and other countries. Data subject to change. Copyright © 2005-2011 Avago Technologies. All rights reserved. AV02-1337EN - August 19, 2011

Polybrominated diphenylether (PBDE) PBDE