The Design uses 74LVC circuits. They are not that fast as ECL logic, but 50 MHz should be possible. Here we make use of the fact, that a phase shift of 180 degress (you mayst call that inverter) at a frequency f0 equals a phase shift of 90 degres at f0/2. We therefore use two D-type Flip Flops to half the frequency. And the clock of one of these is inverted.

We carefully selected an inverter as well as a buffer with the same propagation delay of typically 2.0 ns @ a supply voltage of 3.3 V (from NXP). Using similiar devices from other manufacturer may ruin your day.

The word "budget" applies for power consumption as well as for price.

Input is 30 MHz TTL (DS345). Output is 15 MHz



Input is 100 MHz (SMC100A) with Bias-T. Output is 50 MHz. Scope-BW is 100 MHz :-(


For mixing applications, a lowpass is not always necessary. Some mixers perform best, when using a square wave local oscillator.

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