IEEE Circuits and Systems Magazine - Q1 2022 - 58

D. Carrier-Less UWB Transceiver
for WPAN Applications
A carrier-less impulse-based UWB transceiver is proposed
in [35], and the die photograph of the chip is shown in
Fig. 18(b). In Fig. 21, the architecture of the 802.1.5.4a UWB
transceiver is demonstrated, where the transmitter can
generate PPM UWB pulses with a high-order derivation.
The UWB antenna is used to emit the pulses [35]. The
scheme of the pulse generator is illustrated in Fig. 22,
where UWB pulses are generated by combining different
delayed edges, and then the pulses are filtered [35]. The
shape and spectrum of the output pulse can be varied
by delayed edge combination. Both position modulation
(2-PPM) and polarity modulation (BPSK) can be implemented
by the pulse generator to convey data, where four
delayed synchronous clocks
Cl ,k1
Cl ,k2
Cl ,k3
and Clk4
are
used to generate UWB pulses with wide power spectral
density (PSD). As shown in Fig. 23, the measured TRX
outputs are at 100Mb/s and 200Mb/s data rates.
RX
LNA
dc-Offset
Cancellation
LPF
VGA
Differential Pulse
Generator
PSA
TX
2
DLL
WPA
ADC
Clock
Generator
Pulse
Generator
Figure 21. Architecture of UWB transceiver system [35] © 2006 IEEE.
E. UWB Transceiver for Communications
and Sensing
The UWB transceiver needs to operate within the UWB
spectral mask and FCC limit [2]. The die photograph of
a proposed UWB transceiver [37] for communications
and localization is shown in Fig. 18(c). The system architecture
of the UWB transceiver is shown in Fig. 24. The
transmitter contains the analog baseband pulse generation
and shaping module, where the binary phase-shift
keying (BPSK) modulation is implemented. The receiver
includes the switching channel RF front end and a coherent
(I) and quadrature (Q) demodulation module. A multitone
frequency generator is used
where one VCO core can generate
9 frequency tones based on an alldigital
tuning loop. The blocks, including
the baseband pulse shaping
filter (BPSF), the BPSK module,
the up-conversion mixer, and the
drive amplifier, are integrated onchip
to form the transmitter. A
third-order low pass filter (LPF)
implemented in Gm-C architecture
with dedicated pole and zero placements
is used. The BPSK modulator
is demonstrated in Fig. 25, where
four switches are controlled by
modulation data. The drive amplifier
can operate with a gain from 6 dB
to 8 dB, a maximum output of 8 dBm,
and a bandwidth of 6 GHz coverBaseband
RX
Data
AGC
Synchronizer
TX Data
VDD = 1.2 V GND
D1
D2
D3
D4
Polarity CTRL
Clock (PRF)
PPM CTRL
D
D
D
Clk1
Clk2
Clk3
Clk4
Q
Q
Q
Q
Clk1 Clk2 Clk3 Clk4
-PPM
MUX
D Q
Figure 22. Scheme of UWB pulse generator [35] © 2006 IEEE.
58
IEEE CIRCUITS AND SYSTEMS MAGAZINE
Delay Line
D
D Q
ing the 3 GHz to 9.5 GHz spectrum
[37]. The receiver can operate in either
low band or high band, where
channel 1 to channel 4 operate at
frequencies from 3.1 GHz to 5 GHz
while channel 5 to channel 12 operate
at frequencies from 6 GHz to
9.5 GHz. The output of the LNA will
go through the transconductance
coupled I/Q down-conversion mixers;
then, the down-converted signal
is processed by the VGA with a
dynamic gain from −20 dB to 50 dB
with 400 MHz bandwidth. The circuits
implementing localization are
demonstrated in Fig. 26, where a
phase detector is served as an edge
detector for localization [37]. Ranging
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