Microwave Electronics Products

Model 7928A Miniaturized 8 Bit Digital 360 Phase Shifter Frequency Translator

Application Notes for Microwave Phase Shifters

The Model 7928A is a miniaturized, hermetically sealed PIN diode phase shifter covering the frequency range from 6 to 18 GHz providing a full 360° range of variable phase shift. It can also be used to perform frequency translation.

The unit is an integrated assembly of an RF vector modulator and a driver circuit consisting of an 8-bit D/A converter and a voltage buffer. See Figure 1.

PHASE SHIFT

Phase shifting is achieved utilizing the RF vector modulator approach shown in Figure 2. The 3-dB hybrid coupler divides the RF signal into two quadrature components which are then biased in proportion to the sine and cosine of the desired phase shift. The signals are then combined in-phase to yield desired output.

ACCURACY

Improved phase accuracy and PM/AM performance are achieved by using double-balanced bi-phase linearamplitude modulators. In the main operating band, overall phase accuracy is better than 12°. The same phase accuracy can be achieved at the band edges byusing a built-in frequency correction circuit.Switching speed is better than 500 nsec.

FREQUENCY TRANSLATION (SERRODYNING)

In the design of the Model 7928A special attention has been paid to those characteristics which affect its performance as a frequency translator. These include minimizing PM-to-AM conversion, use of high slew rate drivers, and optimizing phase shift linearity with applied signal. As a result, carrier and sideband suppression levels of over 25 and 20 dB, respectively, are obtained in the main band. The same carrier and sideband performance can be realized over the full stretch band when the internal frequency correction circuit is employed. See Fig. 3 for input control requirements.

On special order, frequency translators can be provided for operation over reduced bandwidths with suppression levels of up to 40 dB. Consult the factory for such requirements.

RF vector modulator diagram, Model 7928A
Fig 2-RF Vector Modulator
  • 6 to 18 GHz
  • 360° range
  • High speed
  • Digitally programmable (8 Bits)
  • Guaranteed monotonicity
  • Hermetically Sealed
  • Miniaturized: < 1.5 inches3
Miniaturized digital phase shifter/frequency translator Model 7928A 
Model 7929 phase shifter block diagram
Fig 1-Model 7928A, block diagram
PHASE SHIFTER SPECIFICATIONS
FREQUENCY RANGE (GHz)
INSERTION
LOSS (Max.)
VSWR (Max.)

ACCURACY   (Max.)

PM/AM (Max.)

Main Band 8.0-18.0
Stretch Band 6.0-18.0
12.0 dB 2.0:1 ±12°
±15°
±1.1 dB
±2.0 dB

Operating Note: To initialized the unit after power up, at least one of the digital bits has to change its TTL level.

FREQUENCY TRANSLATOR SPECIFICATIONS
TRANSLATION RATE (Min.)
CARRIER (1) SUPPRESSION (Min.)
SIDE BAND SUPPRESSION (Min)
INSERTION LOSS
VARIATION (Max.)
with translation rate of:
0 to 500 kHz (2)
Main Band: 25 dB
Stretch Band: 18dB
Main Band: 20dB
Stretch Band: 15 dB
200kHz: 1dB
500kHz: 3dB

NOTES:

(1) When operating as a Phase Shifter outside the Main Band Frequency Range, a TTL Low (0) applied to the J3
      Power/Control Connector Freq. Correction Pin (pin R) will result in Stretch Band Frequencies exhibiting
      enhanced erformance characteristics. The resultant Accuracy and PM/AM speciications will be the same as
     
those shown for the Main Band Frequency Range. When using the unit as a Frequency Translator, similar
      enhanced performance can be achieved for Carrier & Sideband Suppression.


(2)   All speciications are met using only the ive most signiicant bits for translation rates of 0 to 200 kHz. For
       translation rates of 201 to 500 kHz, only 4 most signiicant bits are used.
PERFORMANCE CHARACTERISTICS
Phase Shift
  Range .................................................... 360° in 256 steps
  Variation ................................................ 0.1°/C°
Control Input ................................ 8 bit TTL
Switching Speed  ......................
   (50% TTL to within 10° of
   Final Phase Value)
500 nsec max


Harmonics ....................................... -30 dBc
Power Handling Capability

   Without Performance
   Degradation .........................


+20 dBm 
   Survival Power ......................................... +30 dBm
Power Supply Requirements


+5V ± 5%, 80 mA max
+ 12 to 15V, 10 mA max
-12 to -15, 95 mA  max
Model 7928A phase shifter/frequency translator input requirements
Fig 3-Model 7298A input requirements
ACCESSORY FURNISHED AVAILABLE OPTIONS
Malting power/control connector

  Option no. 

    Description

     

ENVIRONMENTAL RATINGS

7

Two SMA male rf connectors

Operating Temperature
   Range
..............................................................................

-54° to + 95°

10

One SMA male (J1) and one SMA female (J2) rf connector

Non-Operating Temperature
   Range
...............................................................................

-65° to + 125° C

49

High Rel screening per the following Table 1.

G09

Guranteed to meet environmental ratings

 

Table 1. Option 49 High Rel Screening
Kratos General Microwave’s hermetically-sealed products utilize rugged construction techniques and hermetic sealing to meet stringent military requirements for shock, vibration, temperature, altitude, humidity, and salt atmosphere.  All hermetically-sealed parts may be ordered, if desired, with 100% screening in accord with the following MIL-STD 883:

      TEST
METHOD
CONDITION
Internal Visual
2017
--
Temperature Cycle
1010
B
Mechanical Shock
2002
B
Burn-In (at + 110°C)
1015
--
Leak
1014
A1 & A2
Model 7928A phase shifter/frequency translator dimensions and weights