Biomedical Engineering Reference
In-Depth Information
Triangular Pulse Generator
Mixer
PPM
Modulator
Inverter
Integrator
Ring Activation
Circuit
Ring Oscillator
Triangular pulse
generator input
V
ref
Triangular pulse
generator output
Fig. 4.3
Triangular pulse based up-conversion pulse generator
The use of an integrator for triangular pulse generation increases the power
consumption of the circuit. A more efficient triangular pulse generation mecha-
nism using logic gates is described in [
13
], where the triangular pulse is generated
by edge combining the rising and falling edges of a square wave with an inverted
version of itself.
The up-conversion pulse generation technique has the same advantages as the
base band pulse generation technique. Additionally, the spectral shape of the final
pulse can be determined in the base band domain in this method. Consequently,
baseband pulse shaping techniques can be applied to this method rather than
shaping the pulses at high frequencies. Hence, this approach minimizes the use of
the power hungry RF components. However, this method also suffers from the
relatively high power consumption in the mixer and the oscillator.
4.2.3 Waveform Synthesis (Pulse Shaping) Techniques
for UWB Pulse Generators
In some UWB pulse generators, UWB pulses are directly synthesized in the tar-
geted frequency range using pulse-shaping techniques. Unlike base band pulse
generators, this type of UWB pulse generators do not use a base band pulse stream
to filter out the signals with spectral portion at the target frequency range. It uses
