Wide Bandwidth 90 Degrees Phase Shifter for Lock …

1 1. DIPARTIMENTO DI ELETTRONICA. E INFORMAZIONE. wide Bandwidth 90 Degrees Phase Shifter for Lock- in amplifiers Marco Vergani Davide Bianchi Advising Professor: Giorgio Ferrari Analog Design Contest - texas instruments - 13/11/2012. 90 Phase Shifter for lock- in amplifiers 2. IMPEDANCE MEASUREMENTS. BIO-APPLICATIONS MATERIAL SCIENCE OPTICS. INPUT A. REFERENCE x cos( ). SIGNAL 2. cos( t ). A. cos( t ) DC OUTPUT. From Hz to MHz 2. x A. sin( ). frequency span 2. 90 Shifter 90 shifte r Typical architecture: local oscillator required Analog Design Contest - texas instruments - 13/11/2012. 90 Phase Shifter Concept 3. Precise 90 delay Amplitude Recovering Single-pole filter Variable Gain amplifier AIN. - VOUT. VGA AIN. VIN +. Vg Signal processing Negative feedback loop Analog Design Contest - texas instruments - 13/11/2012. 90 Phase Shifter Concept 4.

2 Phase shift 90 Vout Single pole VGA. circuit Vg Vin Specifications Cint 90 shift Negative Positive Output amplitude peak peak +. - independent to extraction extraction frequency Rint Rint Proposed Solution Precise 90 delay through single pole network Input and output amplitude matching through a Variable Gain amplifier and a DC negative feedback Analog Design Contest - texas instruments - 13/11/2012. Quasi-peak detector configuration 5. Vout Rint Cint - + Vg Vin Rint Asynchronous peak sampling and discharge ripple on Vg VGA Harmonic distortion increasing at low frequency Analog Design Contest - texas instruments - 13/11/2012. Synchronous peak comparison 6. Vout Rint Cint - NO RIPPLE. at any Vin + Vg frequency Rint Asynchronous peak sampling Synchronous discharge NO RIPPLE TO BE FILTERED. Analog Design Contest - texas instruments - 13/11/2012.

3 90 Phase Shifter architecture 7. OPA4354 wide bandwith CMOS OTA amplifiers 3 ICs TLC3704 Logic 5V push-pull linear comparators LMH6503 Linear VGA amplifier C. 1. R Phase Vout - V shift VGA. +. R C. 3. Vout + 90 . V. C. 2. - Time Vin Vg V. Vin Vin +. - R R x1 x1. Cint Vout +5V. +. - Open Open Open C 1 2. 1. Close Close V SW1 Rint SW2. Close Close Rint C SW3. 2. Open Open V SW4. Close Close CS1 3 VA VB 3 CS2. C. 3. Open Open V. Analog Design Contest - texas instruments - 13/11/2012. Experimental Results & Outlook 8. 4 decades frequency span: 30Hz -300kHz Leakage from the switches Switches speed Phase Error < 3 . Amplitude precision limited by mismatched charge injection of the discrete MOSFETs switches. Designing of a Reference x DC Real complete IC OUT. Input DC Imaginary embedded lock-in 90 Shifter x OUT. Analog Design Contest - texas instruments - 13/11/2012.

4 9. Thank you for the attention Analog Design Contest - texas instruments - 13/11/2012. Amplitude error 10. VB. Rint Cint Vout - Vg VA. +. Vin Rint Analog Design Contest - texas instruments - 13/11/2012. Digital signal generation 11. Required to control the switches (discrete MOSFETs) Time Vin No external clock required: synchronous with the input signal Time Vin 1. Vout R. Vout - Open Open Open Time Vout +. Vin R 3. 1. + Close Close Open Open Open - Close Close 2. Vout 2 1. Close Close Vin + Open Open Close Open OpenClose Open - R Close Close R. 3 12. +5V Open Close Open Close Open Open Close CloseClose Close Squared input sinusoids 23 Open Open OpenOpen Logic elaboration Close Close Analog Design Contest - texas instruments - 13/11/2012. 3.