13

U2794B

4653C–CELL–06/03

Description of the

Evaluation Board

Board material: epoxy;

er = 4.8, thickness = 0.5 mm, transmission lines: Z

The board offers the following functions:

•

Test circuit for the U2794B:

–

The supply voltage and the control inputs GC, PC and PU are connected via

a plug strip. The control input voltages can be generated via external

potentiometers; then the inputs should be AC-grounded (time requirements

in burst mode for power up have to be considered).

–

The outputs I, IX, Q, QX are DC coupled via an plug strip or can be AC-

connected via SMB plugs for high frequency tests e.g. noise figure or s-

parameter measurement. The Pins II, IIX, QQ, QQX allow user-definable

filtering with 2 external capacitors CII, CQQ.

–

The offsets of both channels can be adjusted with two potentimeters or

resistors.

–

The LO- and the RF-inputs are AC-coupled and connected via SMB plugs. If

transmission line T3 is connected to the RF-input and AC-grounded at the

other end, gain and noise performance can be improved (input matching to

50

W).

–

The complementary RF-input is AC-coupled to GND (CRFX = 1 nF), the

same appears to the complementary LO input (CNLO = 1 nF).

•

A calibration part which allows to calibrate an s-parameter analyzer directly to the in-

and output- signal ports of the U2794B.

•

For single-ended measurements at the demodulator outputs, two OPs (e.g., AD620

or other) can be con-figured with programmable gain; together with an output-

divider network RD = 450

W to RL = 50 W, direct measurements with 50 W load

impedances are possible at frequencies t < 100 kHz.