An Ultra-Wideband Sensor Node Development with Dual-Frequency Band for Medical Signal Monitoring - Ultra Wideband Wireless Body Area Networks - page 86

Pulse generator

V DD A

V DD

b

V DD C

d

Buffer 1

V DD B

a

XOR

Square wave
generator

c

Buffer 2

VDD

Square Wave
Oscillator

a

VDDA
VIH XOR

b

Buffer 1

VIL XOR

t p1

VDDB

VIH XOR

c Buffer 2

VIL XOR

t p2

VDDC

d

XOR

VIH XOR - Input high voltage of the XOR gate

VIL XOR - Input low voltage of the XOR gate
t p1 - Propagation delay of the Buffer 1
t p2 - Propagation delay of the Buffer 2

Fig. 5.4 IR-UWB pulse generation a output of the square wave generator b, c output from buffer
1 and 2 d narrow pulse stream after the XOR gate

C L
2V DD

1
k 1

þ 1
k 2

t p ¼ ð 5 : 1 Þ

where t p is the propagation delay caused by the buffer, C L is the load capacitance,
V DD is the supply voltage of the buffer, and k 1 , k 2 are the gain factors. By passing