전자파 연구실 Microwave amplifier design

전자파 연구실 2 Microwave amplifiers Low noise amplifier Broad band amplifier Power amplifier DC bias ( 동작점 ) 에 따라 트랜지스터의 S-parameter 가 달라짐.

전자파 연구실 Two port power gains 1.Power gain = G = P L /P in : ratio of power dissipated in the load Z L to the power delivered to the input of the two-port network. 2.Available gain = G A =P avn /P avs : ratio of the power available from the two port network to the power available from the source 3.Transducer power gain = G T = P L /P avs : ratio of the power delivered to the load to the power available from the source. If the input and output are both conjugately matched to the two-port, then the gain is maximized and G= G A = G T.

전자파 연구실 4 Output reflection Input reflection (Input impedance)

전자파 연구실

Power gain

전자파 연구실 7 Available gain Transducer power gain

전자파 연구실 8 Conjugate matched case Unilateral transducer gain: S 12 =0

전자파 연구실 Stability If the input or output port impedance has a negative real part, oscillation is possible. 1.Unconditional stability : |Г in |<1, |Г out |<1 for all passive source and load impedances. ( |Г s |<1 and |Г L |<1 ) 2.Conditional stability : |Г in |<1, |Г out |<1 for a certain range of passive source and load impedances.

전자파 연구실 Output stability circle Stability circles

전자파 연구실 Case 1) Case 2) Case 1) Case 2)

전자파 연구실 Input stability circle Case 1) Case 2) Case 1) Case 2)

전자파 연구실 Test for unconditional stability : K-Δ test 원 내부 영역이 |Γ in |=1 인 원과 겹치지 않으면 됨. (1) K-Δ test (2) μ test

전자파 연구실 Example 11.2 Transistor stability

전자파 연구실

11.3 Single-stage transistor amplifier Design for maximum gain (Conjugate matching) (1) Maximum power transfer from the source to the transistor (2) Maximum power transfer from the transistor to the load 아래 식에 대해 연립 방정식 풀어야 함

전자파 연구실

Example 11.3 Conjugately matched amplifier design

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1

Transducer power gain Unilateral transducer gain: S 12 =0 Unilateral figure of merit Unilateral figure of merit :

전자파 연구실 Impedance matching

전자파 연구실 x R r=2 r=1 r=0.5 r=0 x R x=2 x=0.5 x=1 x=-0.5 x=-1 x=-2 Constant resistance, reactance circles

전자파 연구실 25 Impedance-admittance chart 1 Z L = 200-j 100  Z 0 = 100  f = 500MHz Add shunt C Add series L

전자파 연구실 26 Basic Smith chart operation 1. Translation 2. Add series element L C

전자파 연구실 27 L C 3. Add shunt element

전자파 연구실 28 Figure 5.3a (p. 226) Solution to Example 5.1. (a) Smith chart for the L-section matching networks. Z L = 200-j 100  Z 0 = 100  f = 500MHz Example 5.1

전자파 연구실 Single stub tuning Translate by ‘d’ Z L = 60-j 80  Z 0 = 50  f = 2GHz D 를 변화시켜 1+jb 원의 원주 상에 y L 이 오도록 한다.

전자파 연구실 30 Add shunt stub (shorted) 1+jb 원의 원주 상의 지점을 shunt stub( 병 렬 stub) 을 달아서 Γ 원의 원점으로 옮기 면 impedance matching 이 완료됨.

전자파 연구실 zL 이 1+jb 원의 원주 상에 올 수 있도록 d1 을 조절한다. ( 점선 원 ) 상에 z L 이 옮겨 올 수 있 도록 L1 을 조절한다. Impedance matching 순서

전자파 연구실 Unilateral case Without feedback, Without r b’c and C c, this transistor become unilateral. The impedance matching becomes very simple job.

전자파 연구실 Stabilization method 트랜지스터가 unstable 한 경우 직렬 또는 병렬로 저항을 연결하면 안정도가 바뀐다. Input stability and or

전자파 연구실 Output stability or The corresponding condition is

전자파 연구실 Neutralization or unilateralization

전자파 연구실 Constant gain circle and design for specified gain Without feedback, an amplifier becomes unilateral. G S, G L are maximized when g S, g L are defined as normalized gain factors

전자파 연구실

Figure 11-8b (p. 557) (b) RF circuit. (c) Transducer gain and return loss.

전자파 연구실 Low noise amplifier design :Source admittance presented to transistor :Optimum source admittance that result in minimum noise figure. : Minimum noise figure of transistor, attained when :equivalent noise resistance of a transistor :Real part of source admittance

전자파 연구실 Figure 11-9b (p. 561) (b) RF circuit.

전자파 연구실 11.4 Broadband transistor amplifier design

전자파 연구실 Balanced amplifier Figure (p. 562) A balanced amplifier using 90° hybrid couplers. : Incident input voltage The output voltage can be found as

전자파 연구실 Figure (p. 564) Gain and return loss, before and after optimization, for the balanced amplifier of Example The total reflected voltage at the input can be written as

전자파 연구실 Distributed amplifiers Very wideband width Good input and output matching Not good noise figure Not very high gain Occupies large area Equivalent circuit for one FET

전자파 연구실 Figure (p. 566) (a) Transmission line circuit for the gate line of the distributed amplifier; (b) equivalent circuit of a single unit cell of the gate line. Figure (p. 566) (a) Transmission line circuit for the drain line of the distributed amplifier; (b) equivalent circuit of a single unit cell of the drain line. Gate equivalent circuit Drain equivalent circuit

전자파 연구실 Gate transmission line equivalent circuit

전자파 연구실 Drain transmission line equivalent circuit

전자파 연구실 Gate source voltage on n-th FET : Total output current on N-th terminal of of the drain line:

전자파 연구실

부품 라이브러 리

전자파 연구실

시물레이션 시 작

전자파 연구실

Stability

Stability