Application Notes for: Microwave Phase Shifters, IQ Vector Modulators & Frequency Translators
Both Series comprise a family of four solid-state PIN diode I-Q Vector Modulators covering the frequency range from 0.5 to 18 GHz in four bands: 0.5 to 2 GHz, 2 to 6 GHz, 4 to 12 GHz and 6 to 18 GHz. See Fig. 1.
All models provide a full 360° range of phase shift and a minimum of 20 dB attenuation range at any frequency.
- Simultaneous control of amplitude and phase
- 0.5 to 18 GHz in four bands: 0.5 to 2 GHz; 2 to 6 GHz; 4 to 12 GHz; 6 to 18GHz
- 12 Bit digitally programmable (Series 71)
- Analog control (Series 72)
- High speed
- Guaranteed monotonicity
THEORY OF OPERATION
The block diagram of the I-Q Vector Modulator is shown in Figure 1. An RF signal incident on a 3 dB quadrature hybrid is divided into two equal outputs, with a 90° phase difference between them. The in-phase, or 0°, channel is designated the I channel and the Quadrature, or 90°, channel is designated the Q channel. Each signal passes through a biphase modulator which sets the 0° or 180° state and the attenuation level for both the I and Q paths. The outputs of the I and Q path are combined to yield the resultant vector which may fall anywhere within the bounded area shown in Figure 2. Any signal applied to the I/Q Vector Modulator can be shifted in phase and adjusted in amplitude by applying the following relationships:
- Let the desired attenuation level = X dB and the desired phase shift
- The normalized output voltage magnitude is given by:
- The values of the I and Q attenuator control inputs are then expressed as:
I = V cos θ
and
Q = V sin θ
Figure 3 shows the nominal value of I and Q vs. either digital word (Series 71) or analog voltage (Series 72). Thus, to achieve an attenuation level of 3 dB with a phase offset of 112.5° (with respect to 0 dB and 0° reference states) the values of I and Q can be calculated as follows:
V = 10–(3/20) = 0.707
I = 0.707 cos (112.5°) =–0.027
Q = 0.707 sin (112.5°) = +0.65
From Figure 3, the control inputs to yield the desired amplitude and phase are approximately:
| Analog Units (72 Series) | Digital Units (71 Series) |
|---|---|
| I = 5.78 volts | 100101000000 |
| Q = 2.84 volts | 010010001011 |
While these values for I and Q will yield an output signal whose amplitude and phase are close to the nominal values over the entire operating frequency range of the vector modulator, the use of an iterative measurement procedure will determine the I and Q inputs which exactly define the desired parameter at any selected frequency.
| MODEL | 7120/7220 | 7122/7222 | 7124/7224 | 7128/7228 |
| FREQUENCY | 0.5-2.0 GHz | 2.0-6.0 GHz | 4.0-12.0 GHz | 6.0-18.0 GHz |
| INSERTION LOSS | 13 dB | 11 dB | 12 dB | 12 dB |
| VSWR (MAX) | 1.6:1 | 1.8:1 | 1.8:1 | 2.0:1 |
| POWER HANDLING Without PERFORMANCE DEGRADATION | +7 dBm | +20 dBm | +20 dBm | +20 dBm |
| SURVIVAL POWER (MAX) | 1W | |||
| ABSOLUTE INSERTION PHASE ACCURACY VS. FREQUENCY (MAX) | ±15o | |||
| VARIATION OF PHASE VS. TEMPERATURE (MAX) | ±0.1 deg./ oC | |||
| ATTENUATION RANGE (MIN) | 20 dB | |||
| VARIATION OF AMPLITUDE VS. TEMPERATURE (MAX) | 0.02 dB/ oC | |||
| RESPONSE TIME (MAX) | 0.5 µsec | |||
| POWER SUPPLY |
-12 to -15V @ 70 mA +12 to +15V @ 70 mA |
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| CONTROL INPUT | ||||
| 71 SERIES | 12 bit TTL for both I and Q inputs | |||
| 72 SERIES | 0 to +10V DC for both I and Q inputs | |||
| CONTROL INPUT IMPEDANCE | ||||
| 71 SERIES | 40 µA max | |||
| 72 SERIES | 10 kohm | |||
RECOMMENDED SEQUENCE OF POWERING THE SUPPLIES
| 1. | Set command lines to logic level “0”. |
| 2. | Turn on the -12 to -15V power supply. |
| 3. | Turn on the +12 to +15V power supply. |
| 4. | Turn on the +5V power supply. |
| 5. | Set command lines to logic level “1”. |
| 6. | Now you can start to work (if you want for example zero phase, set again all control lines to “0”) |
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ENVIRONMENTAL RATINGS – OPTION G09
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ACCESSORY FURNISHED
AVAILABLE OPTIONS
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DIMENSIONS AND WEIGHT Series 71
| SERIES 71 | |||||||||
| MODEL | A | B | C | D | E | F | G | H | J |
| 7120 | 4.95±.03 (125,7) |
3.38±.03 (85,9) |
1.02 (25,9) |
4.75±.01 (120,7) |
3.12±.01 (79,2) |
2.62 (66,5) |
1.69 (42,9) |
2.47 (62,9) |
.73 (18,5) |
| 7122 |
3.25±.03 (82,6) |
3.25±.03 (82,6) |
.85 (21,6) |
3.05±.01 (77,5) |
3.00±.01 (76,2) |
1.63 (41,4) |
1.99 (50,5) |
1.63 (41,4) |
.64 (16,3) |
| 7124 | 1.83 (46,5) |
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| 7128 | 3.00±.03 (76,2) |
3.00±.03 (76,2) |
.96 (24,4) |
2.80±.01 (71,1) |
2.75±.01 (69,9) |
1.50 (38,1) |
1.63 (41,4) |
1.50 (38,1) |
.76 (19,3) |
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DIMENSIONS AND WEIGHT Series 72
| SERIES 72 | |||||||||
| MODEL | A | B | C | D | E | F | G | H | J |
| 7220 | 4.95±.03 (125,7) |
3.38±.03 (85,9) |
1.02 (25,9) |
4.75±.01 (120,6 |
3.12±.01 (79,2) |
1.68 (42,7) |
0.75 (19,1) |
1.75 (44,5) |
73 (18,5) |
| 7222 |
3.25±.03 (82,6) |
3.25±.03 (82,6) |
.85 (21,6) |
3.05±.01 (77,5) |
3.00±.01 (76,2) |
1.63 (41,4) |
1.99 (50,5) |
0.90 (22,9) |
.64 (16,3) |
| 7224 | 1.83 (46,5) |
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| 7228 | 3.00±.03 (76,2) |
3.00±.03 (76,2) |
.96 (24,4) |
2.80±.01 (71,1) |
2.75±.01 (69,9) |
1.50 (38,1) |
1.63 (41,4) |
0.78 (19,8) |
.76 (19,3) |
| MODEL | WEIGHT (APPROX) |
| 7220 7222 7224 7228 |
13 oz. (369 gm) 10 oz. (284 gm) 10 oz. (284 gm) 9 oz. (255 gm) |
Dimensions in mm (Inches) Tolerances, unless otherwise indicated: .XX ±.02; .XXX ±.005