A Push-pull Self Oscillating Mixer Design Based On Foundry Services
Olaniyi Jinadu, Dewakar Madapuci Kanday, Prof. Afshin Daryoush
Electrical and Computer Engineering Department, Drexel University, Philadelphia, Pennsylvania 19104, USA
Introduction
Differential Amplifier: ADS Modeling
 Microwave local oscillators (LO) are used for frequency
translation from baseband/intermediate frequency (IF) to radio
frequency (RF) signals using mixers.
 The concept of self‐oscillating mixers (SOM) is very attractive to
achieve high dynamic range and conversion efficiency in mixers
by combining both oscillation conditions in circuits and
nonlinear mixing.
 Self‐oscillating mixer eliminates the need for a buffer amplifier
that has to be used after conventional mixers.
Push-Pull Self-Oscillating Oscillator
 Oscillator Gain at oscillation frequency
 A resonant circuit at 5GHz is designed using a band‐stop filter and
provides positive feedback between based and collector separate
transistor pairs to build oscillator at 5GHz and use 2nd harmonic
generation at 10GHz
 Band-stop filter schematic for 5GHz
Design Procedure
 Si‐Ge/Si HBT device parameters from IBM and Si CMOS
technology from TSMC are considered to implement the SOM
at 10 GHz for mixing with IF/RF signals.
 The foundry parameters are employed to plot transistor DC I‐
V device and design load lines for appropriate operation
point.
 The push‐pull amplifier is designed for operation in class AB
as a building block of oscillator.
 The source current of push‐pull amplifier is used for mixing of
IF and LO signals to generate RF.
Pick best operation point for low noise and gain
Design a differential amplifier
Provide IF/RF for self‐oscillation mixing
 Circuit schematic using Agilent ADS
 Oscillator circuit schematic using Agilent ADS
Conclusion
 Differential Operation: Vin2 – Vin1 = V1
RFout
RF in
Add resonant circuit and build positive feedback oscillator
 Demonstrated the design and implementation of both differential
amplifier and differential oscillator
 Band‐stop filter was modeled at resonance frequency of 5 GHz
 The performance of the differential oscillator (gain) was observed as
the oscillator should oscillate at 10 GHz with a gain of at least 3 dB
Future Design Modifications
 Optimize design to observe high gain oscillation at 10 GHz
 Implement the mixing operation to the oscillator to make it a self‐
oscillating mixer
Tune oscillation frequency
 Insertion gain at 5 GHz with insertion loss at 10GHz
Advantages of Self-Oscillating Mixers
 The self‐oscillating mixer is a combination of both the
oscillating and mixing circuit functions required in
independent blocks of an oscillator and mixer.
 A push‐pull circuit topology will result in a lower power
consumption oscillator and more efficient mixing functions.
 Using an external frequency reference or using a self injection
locking, frequency of the local oscillator is stabilized
 The stabilized source of 10GHz is used for realization of clock
reference in distributed systems.
 In order to make the oscillator portion frequency and phase
stabilized, self forced oscillation (e.g. dual self‐injection locked
and phase locked loops) can be used
Differential Amplifier Circuit
 Amplifier Gain: Output Power (dB) – Input
Power (dB)
 Fabricate and obtain experimental data of the push‐pull amplifier and
self‐oscillating mixer using FR4 substrate specifications
 Correlate between the simulations and the experimental data
 Optimize design to increase the gain and output power signal while
reducing the noise at other frequencies even more
 Implement the phase locking (PL) and phase locked loop(PLL)
operations to the self‐oscillating mixer to create an injection locking
phase‐locked loop self‐oscillating mixer
Potential for oscillation at 5 GHz and Harmonic Content