This document provides an overview of RF circuit design topics including: - Active filters and cable repeaters - Single-stage amplifier design including gain, noise figure, and matching networks - Power amplifier design including calculating the required load resistance based on supply voltage and desired output power, designing matching networks to transform impedances, ensuring stability over temperature and voltage variations, and verifying device ratings are not exceeded. The document notes that ensuring power amplifier stability often requires the most design effort and that the collector DC circuit impedance significantly impacts stability.

1. 射頻電路設計實務
Filter
RF Circuit Design for Systems
(射頻電路設計實務 4D9090)/課程共筆
講師 : 許智威 (owner , IEEE member) Mail :
awei@ieee.org ; 四電通四A ; 教室 : I2603 ;

2. • Active Filter
• Cable Repeaters
𝐹 𝑇
𝑛
= 10 𝑙𝑜𝑔[ 1 + 𝑛(𝐹 −
1
𝐺
+ ⋯ )
f = 1/𝜋𝑅𝐶𝑖𝑛
Gain [dB] G -G G -G G -G
Noise Figure[dB] F G F G F G

3. Single-Stage Amplifiers

4. Single-Stage Amplifiers

5. Power Amplifiers
•RL=
(𝑉𝑐𝑐 −𝑉𝑠𝑎𝑡)2
2𝑃 𝑜𝑢𝑡
• RL = Load resistance required
at device output
• Vcc = DC supply voltage (V)
• Vsat = device saturation voltage (V)
• Desired RF power output (W)

6. Power Amplifiers
• RL=
(𝑉𝑐𝑐 −𝑉𝑠𝑎𝑡)2
2𝑃 𝑜𝑢𝑡
• RL = Load resistance required
at device output
• Vcc = DC supply voltage (V)
• Vsat = device saturation voltage (V)
• Desired RF power output (W)
1 . Design a matching network that transforms the system
impedance (50Ω or 75 ) to the required load resistance,
RL , over the required bandwidth. 符合系統阻抗, 操作頻寬
2. Design a conjugate match at the device input when the
output is terminated in the required RL.
3. Verify that the amplifier is stable over temperature and voltage
variations and output voltage standing wave rate (VSWR). This
last task usually takes the most time. The most sensitive
component affecting stability is the collector DC chock. The
impedance of this DC feet circuit must not be too large at low
frequencies.
4. Verify that the device voltage, current and power dissipation
ratings are not exceeded over the operating conditions. The
collector or drain voltage in class-C amplifiers will reach twice the
supply voltage.