RF&BB Signal Conditioning

RF and Baseband Signal Conditioning

Step	Technical Description
1	The baseband bandwidth is defined by the product specifications and RF front-end signal design.
2	After the mixer, the baseband signal is conditioned by the LPF and PGA to limit the signal bandwidth, suppress out-of-band noise, and optimize the signal level before the ADC.
3	The ADC samples the conditioned baseband signal at a fixed sampling rate determined by the system (e.g., 2.5 MHz).

Step

Technical Description

1

The baseband bandwidth is defined by the product specifications and RF front-end signal design.

2

After the mixer, the baseband signal is conditioned by the LPF and PGA to limit the signal bandwidth,

suppress out-of-band noise, and optimize the signal level before the ADC.

3

The ADC samples the conditioned baseband signal at a fixed sampling rate determined by the system (e.g., 2.5 MHz).

1. Signal Flow and Processing

Step1. Given Condition

Allocated bandwidth: 200 MHz ← ISM Band 24.045 GHz ~ 24.245 GHz

Step2. Requirments by a customer

Requirement	Symbol	Typical Value	Design Impact
Max Range Limit	R_max	8 m	R_max(Requirement)→B_BB(System Limit)→T_UP(Design variables)
Range Resolution	ΔR	0.75 m	Defines the RF chirp bandwidth, B_RF = c/2ΔR
Max Velocity Limit	V_max	25 m/s	Constrains the maximum allowable chirp cycle to avoid Doppler aliasing.
Velocity Resolution	ΔV	0.25 m/s	Defines the required CPI, i.e., the number of chirps per frame

Step3. Chirp Design

Name	Symbol	Typical value	Description
RF Chirp Bandwidth	B_RF	200 MHz	Selected $B_RF=200 MHz$ within allocated band
Baseband Bandwidth	B_BB	25.4 kHz	Fixed by system bandwidth limitation (ADC/LPF).
Waveform	–	CW + SAW	Continuous-wave transmission with sawtooth FMCW chirp
Start Time	T_START	20 us	typically fixed, hardware-determined settling time
Down-chirp Time	T_DOWN	150 us	typically fixed, hardware-determined reset/return time
Stop Time	T_STOP	410 us	typically fixed, hardware-determined idle/guard time
Up-chirp Time	T_UP(min)	420 us	The actual value shall be determined by considering the frame structure.