Amplitude Feedback Subcircuit Schematic Modifications Reference Level Shifter

Amplitude Feedback Subcircuit Schematic Modifications Reference Level Shifter Envelope Detectors Feedback Log Amps Error Calculator Attenuator Level Shifter Without level shifters, envelope detector output does not overlap with full input range of log amp. Level shifters increase correction range.

Candidate Topologies for Level Shifters • Op-amp level shifter + Accurate and easily adjusted – Limited bandwidth due to wires splicing it onto PCB • AC coupling + Simple, easiest modification – Blocks low frequency components of signal • Diode level shifting circuit + Simple, easy modification – Some distortion due to voltage drop across diode • Tested each topology on breakout boards and on PCB v Diode level shifter performed best on system board

Phase Detector Output Signals for Single Tone Inputs 500 MHz • Distinct logic “hi” and “low” levels • Well defined square wave output • Accurate phase error measurements 2 GHz • Indeterminate logic “hi” and “low” levels • Not a well defined square wave output • Invalid phase error measurements

Phase Detector & Error Measurement Subcircuit Schematic Phase Shifter Error Calculator Proposed modifications: • Prescaler (frequency divider) • Reduce frequency by ½ or ¼ • Tested successfully 1 -tone Phase Detector • Comparator • Clean up inputs (fast rising edge) • Testing evaluation boards • Both subcircuits are “add-ons” Phase FB Vref Comparator Prescaler Attenuator Prescaler Comparator Phase Ref Vref

Candidate Prescalers & Dividers On Semi Prescalers & Dividers* Part # Description Propagation Delay (p. S) Not specified Rise & Fall Times (p. S) Not specified MC 12095 NB 7 L 32 M 2. 5 GHz prescaler, 2 or 4 2. 5 V, CML, 2 200 30 MC 10 EP 32 3. 3 V, ECL, 2 350 120 MC 10 EL 33 5 V, ECL, 4 650 225 * Initially limiting candidates to On Semi components to ensure compatibility w/ phase detector Test Status: the MC 12095 was tested successfully at 2. 14 GHz

Circuits for Sharp Input Edges • Schmitt Trigger Inverters – Commercially available • SN 74 AUC 1 G 04 VH = 1. 2 V, 0. 8 n. S propagation delay • NLX 3 G 14 VH = 1 V, 4 n. S propagation delay – Non-Commercially available • VH=0. 42 V, 170 p. S switching speed • Comparators – Analog Devices ADCMP 573, propagation delay 150 p. S – On Semi MC 10 E 1651, propagation delay 775 p. S – Linear Technology LTC 5564, typical response time 7 n. S

ADCMP 572 Evaluation Board Measurement Outputs Input f = 5 MHz Typical rise and fall times for ADCMP 57 X are specified as 35 p. S