Resonator 225
Figure 9.11: Equipment setup for W-band 75∼110 GHz phase noise
measurement.
Figure 9.12: Chip photo of the DTL-SRR-based oscillator and SWO.
function of spectrum analyzer is used to verify the source of spurs. However,
the signal power level could be distorted by such identification function, which
should be turned off when capturing the measurement results. The output
power is −16 dBm by subtracting the loss of cable and Bias-T.
Figure 9.15 shows the phase noise measurement and simulation results
of the DTL-SRR and SWO-based oscillators. It can be observed that the
variation of phase noise becomes worse near the oscillation frequency, induced
226 Design of CMOS Millimeter-Wave and Terahertz Integrated Circuits
Figure 9 .13: Spectrum of the 76 GHz DTL-SRR oscillator.
by the modulation of 1/f noise. Thus mo re stable phase noise results at 10
MHz offset are used for comparison. One c an see that the phase noise of DTL-
SRR-based oscillator is 4.2 dB better than that of the SWO at 10 MHz offset
at the oscillation frequency. This phas e noise impr ovement is very close to
2.6 dB observed from simulation results. Note that the phase noise of both
oscillator s are approaching the same level (around -116 dBc/Hz) from 10-
MHz to 100-MHz frequency offset. This is bec ause the phase noise level of
the oscillator is lower than the noise level of the spec trum analyz er in the
measurement.
Table 9.1 summarize s the performance of the proposed DTL-SRR-based
oscillator , the SWO realized in the same chip, and the previous oscillators
by LC-tank or SWOs at the simila r frequency and proces s, and achieves a
phase noise of -108.8 dBc/Hz at 10 MHz offset and a FOM of -182.1 dBc/Hz.
Note that the energy loss is reduced due to the higher power efficiency, thus
the power consumption of DTL-SRR-based oscillator is much smaller than the
SWO-based oscillator while the phase noise is minimized. As a summary, when
compared to the existing LC-tank or sta nding-wave resona tor-based oscillator
[246, 238, 239], the pha se noise and FOM are improved by 2.7 dB and 7.6
dB on average, respectively. When compared to the standing-wave reso nator-
based oscillator implemented on the same chip, the phase nois e and FOM are
improved by 4.2 dB a nd 4.1 dB, respectively.
Resonator 227
Figure 9 .14: Spectrum of the 76 GHz SWO.
Figure 9.15: Phase noise measurement and simulation results of the
76 GHz DTL-SRR oscillator and SWO.
9.4.3.2 Results of 96-GH z Oscillator with DTL-CSRR
The die photo of the 96-GHz Oscillator with DTL-CSRR is shown in Fig ure
9.16 with area of 430 × 320 µm
2
(0.14mm
2
) excluding RF-PADs. Both the
228 Design of CMOS Millimeter-Wave and Terahertz Integrated Circuits
Table 9.1: Performance Comparison of State-of-the-Art Oscillator
Designs around 70 GHz
Parameters
[246] [238] [239] This work This work
Oscillator Design
LC-tank SWO SWO SWO DTL-SRR
f
osc
(GHz)
70.2 71.1 76.5 76.1 76.1
Power Supply (V)
1.2 1.2 1.5 1.0 1.0
Power
core
(mW)
5.4 6 14.3 2.63 2.7
Phase Noise @ 10-MHz
offset (dBc/Hz)
-106.1 -104 -108.4 -104.6 -108.8
FOM (dBc/Hz)
-175.8 -173.2 -174.5 -178 -182.1
Technology
65-nm
CMOS
65-nm
CMOS
65-nm
CMOS
65-nm
CMOS
65-nm
CMOS
Figure 9 .16: Chip photo o f the DTL-CSRR-based oscill ator.
oscillator core and output buffer are supplied with a 1.2-V power supply, of
which the current consumption is 6.24 mA and 6.53 mA, respectively. Thus
the power consumption for the oscillator core circuit is 7.5 mW. Figure 9.17
shows the measured spe ctrum when the output frequency is 96.36 GHz. Same
as the oscillato r with DTL-SRR, there is a 200 MHz offset spur generated
Resonator 229
Figure 9 .17: Spectrum of the 96-GHz oscillator with DTL-CSRR.
Figure 9.18: Phase noise measurement and simulation results of 96
GHz oscillator with DTL-CSRR.
by the harmonic mixer. Figure 9.18 shows the measured phase noise at this
frequency of -111.5 dBc/Hz at 10-MHz offset, which is 4.5dB higher than the
simulation results. This is pro bably due to the noise co upled from the DC
power supply.
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