TABLE OF CONTENTS In order to provide some understanding of mixer operation, a simple single loop circuit will now be analysed.
Consider the simple single-loop circuit shown in Figure 7.3. This represents a single-ended mixer design, where all mixed products and intermodulation products are terminated in the source and load resistances, i.e. a wideband mixer design. This circuit will now be examined using both general non-linear analysis and a method of linear circuits with time-varying parameters. The latter method is also referred to as the conversion loss matrix method.
We begin by combining the source and load resistances with the non-linear device to form a new non-linear equation:
| (7.8) |  |
where a, b, c, d are constants and V is the sum of all applied voltages. In the present analysis, we will restrict the power series to the first two terms. After substituting for V and some trivial manipulation, we have:
| (7.9) |  |
The power available from the signal, P av, is given by:
| (7.10) |  |
Power into the load at any frequency is given by:
| (7.11) |  |
Conversion loss ( CL) is therefore given by:
| (7.12) |  |
For ? RF to ? LO ? RF and ? LO ?RF:
| (7.13) |  |
For ? RF to 2 ? RF and ? LO to 2 ? LO:
| (7.14) |  |
