This thesis introduces a new scheme of reference oscillator called DTCSO (Digitally Temperature Compensated SAW Oscillator). The proposed reference oscillator, DTCSO shows the possibility of one-chip solution of reference oscillator in a RF system.
Until now, most reference oscillator has been implemented using hybrid TCXO which has off-chip crystal resonator, and that is one of the bottlenecks to realize full one-chip RF system. But our DTCSO is realized using high Q SAW (Surface Acoustic Wave) resonator. Comparing with an existing crystal resonator (also called BAW resonator), though SAW resonator has a little bit lower Q-factor and larger frequency drift for temperature variation, it is compatible with conventional thin film batch process and can obtain higher reference frequency ( ＞ 100 MHz).
Contrary to conventional analog temperature compensated SAW oscillator (TCSO), the frequency drift cab be compensated by using simple digital compensation block. They replace the varactor and analog temperature sensor which are hardly integrable on cheap Si IC. Because the digital control block is easily fabricated using contemporary IC technology, low cost and mass producible reference oscillator can be achieved in this way.
From this basis, the 3-chip MCM (Multi Chip Module) DTCSO is fabricated. One is SAW resonator, another is other oscillator part (oscillator, current source, capacitor array and buffer) and the other is temperature sensor, PROM.
All of them except SAW device are designed and fabricated on Si IC using cheap CMOS foundry. Few lumped components are used. And it has 0.2 Vpp voltage swing (at 1 kOhm load), 8mW DC power consumption, -102 dBc/Hz(at 1 kHz offset) phase noise and ±4.5ppm frequency drift from 15°C to 79°C.
