• High-speed TTL programming
  • 50 ohm matched I/O
  • DC to 6 GHz bandwidth
  • Passive switched-line delays
  • Low VSWR
  • 7 Bit (127 step) range
  • 8 bit extended range option
  • 5 ps step size
  • Time or phase shifting
  • Precise repeatability




The PADL6 is a programmable delay line instrument designed for adjusting the time delay or phase of radio, microwave or even digital signals with bandwidths from DC to 6 GHz. Delays are controlled via a TTL level bus.

This instrument is an attractive alternative to either the manually operated, hand-cranked line stretchers which are very time consuming when delays have to be changed frequently and the servo controlled line stretchers which are expensive and wear out quickly. It also has the advantage of lower mismatch, higher bandwidth and higher range than delay lines that use lumped or distributed varactor elements.

The PADL6 programmable delay lines employ all GaAs passive microwave switched-line techniques. Lines are switched in a series configuration so that each delay occurs additively with any other switched-in delay. The signal is DC coupled therefore has no lower band limit. Since no active elements are used, input power as high as 24 dBm may be used and still yield less than 1 dB compression. The delay lines I/O provide a good match of 50 ohms relative to ground yielding a VSWR of less than 1.3 from DC to 5 GHz and less than 1.5 to 6 GHz. This enhances its usefulness in applications where the signal source and termination are not well matched. Poorly matched I/O terminations can generate reflections that may result in delay-shift aberrations when the incident signal and the reflected signal are coincident. Inputs and outputs are connected by SMA jacks. Data, control signals and power are connected by a standard 15 pin D-type subminiature connector plug.. This instrument is provided in low profile rugged aluminum housing and requires a single, low power, 5V power supply making this instrument easy to use.  Internal voltages are regulated to eliminate supply noise coupling to the signal path. 

Delays are controlled to precise 5 picosecond steps with a range of 27-1=127 delay steps or 635 picoseconds or with 'Option A'  28-1=255 delay steps or 1275 picoseconds . When this device is used as a programmable narrow-band phase shifter the phase shifts are proportional to the frequency. The equivalent phase shift, per picosecond delay, is 0.36 deg./psGHz or 2.78 ps = 1 deg/GHz.. The PADL6 is calibrated to maintain a high degree of delay accuracy over the entire operating bandwidth. The accuracy is better than 1 LSB (+/-). This device has high monotonicity. The differential losses between delay elements are balanced so that the total loss does not vary widely between delay states.



The delay line consists of passive GaAs microwave transfer switches. The switch network series resistance losses are matched with shunt resistance to ground for improved wide-band matching.



The diagram above shows the typical transfer characteristics. The differential loss between arbitrary delay states is less than +0.3 dB DC to 3 GHz, +0.5 dB from 3 to 5 GHz and +0.8 dB from 5 to 6 GHz.



Each of the7 programming bits represents a binary number corresponding to a delay state equal to the binary number times the step size. This gives 27=128 possible combinations and a delay range equal to 127 x 5ps. The control word may be latched by using the "LE" latch line (see function diagram and pin-out diagram). The control word need not be latched if the user wishes to operate the latch transparently. Simply keep the latch line high and the delay state will follow the applied data.



  • Pin #__________Function
  • 13-14_________+5.0V Power
  • 1-8____________DO - D6 data, active high   
  • 8______________option A
  • 9-12___________Ground
  • 15_____________LE Latch line, active low 

15 pin, male, D-type subminiature connector



(beyond which damage may occur)


Option A: $150___ Extended range, 8 bit programmable to 1275 ps with MSB on pin #8. Insertion loss increases by approximately 2 dB. PADL6.pdf

Price: PADL6; $1900,   PADL6A; $1950   ____Price and specifications subject to change without notice.

Please use e-mail for any correspondences, either technical or administrative, at address

 GigaBaudics    5266 Hollister Ave. Ste 221 Goleta, CA  93111 (805) 687-5934