晶振仿真问题求助

这是啥

使用皮尔斯振荡器，起振要求反相器跨导gm＞5*gmcrit。这里的反相器跨导是指什么

这是啥

环路增益要怎么仿，仿出来的波形应该是怎么样的？

jzr1989

仿真波形是这样的：

jzr1989

还有这个，找gm_crit用的

love1226

jzr1989 发表于 2020-12-15 18:28
还有这个，找gm_crit用的

能否分享一下你的code,xiexie !!

jzr1989

love1226 发表于 2020-12-17 09:29
能否分享一下你的code,xiexie !!

1. clear;
   
2. clc;
   
3. 
   
4. % Series resonant circuit model of montional osillation
   
5. syms wm fm Lm Cm Rm Q real;
   
6. fm=4.00e6;Cm=5.0e-15;Rm=400.0;% Designer specified parameters:motional resonant frequency
   
7. %,motional capacitance and motional resistance
   
8. wm=2*pi*fm;% Calculate motional resonant angular frequency
   
9. Lm=wm^-2/Cm;% Calculate motional inductance
   
10. Q=1/(wm*Cm*Rm);% Calculate quality factor
    
11. 
    
12. % Ocillator circuit model
    
13. syms Rf C3 C1 C2 Cload gm real;
    
14. Rf=1e6;
    
15. %gm=34.5e-3;
    
16. C3=5.0e-12;C1=16.0e-12;C2=16.0e-12;
    
17. Cload=C1*C2/(C1+C2);
    
18. % Actual ocillation angular frequency
    
19. syms w wa f;
    
20. %w=wm*(1+Cm/(2*(C3+Cload)));% Calculate actual ocillation angular frequency
    
21. w=wm*sqrt(1+Cm/(C3+Cload));% Calculate actual ocillation angular frequency
    
22. f=w/(2*pi);
    
23. 
    
24. wa=wm*sqrt(1+Cm/C3);% Calculate anti ocillation angular frequency
    
25. fa=wa/(2*pi);
    
26. 
    
27. 
    
28. % The mount of frequeancy pulling above wm
    
29. syms p real;
    
30. p=(w-wm)/wm;
    
31. 
    
32. % Motional impedance
    
33. syms Zm;
    
34. Zm=Rm+1i*2*p/(w*Cm);
    
35. 
    
36. % Oscilator circuit impedance
    
37. syms Zc Z1 Z2 Z3 R1 R2 R3;
    
38. %Z1=1/(1i*w*C1);Z2=1/(1i*w*C2);Z3=1/(1i*w*C3+1/Rf);% Rf
    
39. %Z1=1/(1i*w*C1);Z2=1/(1i*w*C2);Z3=1/(1i*w*C3);% For lossless circuit
    
40. R1=inf;R2=inf;R3=inf;
    
41. Z1=1/(1i*w*C1+1/R1);Z2=1/(1i*w*C2+1/R2);Z3=1/(1i*w*C3+1/R3);% For lossy circuit
    
42. Zc=(Z1*Z3+Z2*Z3+gm*Z1*Z2*Z3)/(Z1+Z2+Z3+gm*Z1*Z2);
    
43. 
    
44. % Transconductances
    
45. syms gm_crit gm_max gm_opt Rneg Rneg_max real;
    
46. Rneg=real(Zc);
    
47. gm_opt=solve(diff(Rneg),gm);
    
48. gm_opt=double(gm_opt(2));
    
49. %gm_opt=w*(C1+C2+C1*C2/C3);
    
50. Rneg_max=double(subs(Rneg,'gm',gm_opt));
    
51. %Rneg_max=-1/(2*w*C3*(1+(C1+C2)*C3/(C1*C2)));
    
52. 
    
53. gm_crit_max=double(solve(Rneg==-Rm,gm));
    
54. %gm_crit_max=solve(Rneg==-Rm,gm);
    
55. gm_crit=gm_crit_max(1);
    
56. %gm_crit=(w*(C1*C2+C2*C3+C3*C1)^2)/(Q*Cm*C1*C2);
    
57. gm_max=gm_crit_max(2);
    
58. 
    
59. %Actual gm and Rneg
    
60. gm=0.1e-3:0.1e-4:500.0e-3;
    
61. Rneg=double(subs(Rneg,'gm',gm));
    
62. figure(10);
    
63. semilogx(gm,Rneg,'r-');grid on
    
64. xlabel('gm(S)');
    
65. ylabel('Negative Resistance(ohm)');
    
66. title(['Negative Resistance VS. gm',newline,'fm=',num2str(fm/1000000,'%.f'),'MHz']);
    
67. hold on
    
68. 
    
69. xlim=get(gca,'Xlim');
    
70. plot(xlim,[min(Rneg),min(Rneg)],'b-')
    
71. plot(xlim,[-Rm,-Rm],'m-');
    
72. % plot(xlim,[-200,-200],'c-');
    
73. 
    
74. ylim=get(gca,'Ylim');
    
75. plot([gm_crit,gm_crit],ylim,'k--');
    
76. plot([gm_opt,gm_opt],ylim,'k--');
    
77. plot([gm_max,gm_max],ylim,'k--');
    
78. % plot([10.84e-3,10.84e-3],ylim,'k--');
    
79. % plot([40.37e-3,40.37e-3],ylim,'k--');
    
80. clear xlim ylim;
    
81. text(gm_crit,-Rm,['(gm_crit,-Rm)',newline,'(',num2str(1000*gm_crit,'%.2f'),'m,',num2str(-Rm,'%.0f'),')',newline,newline],'Interpreter','none');
    
82. text(gm_opt,Rneg_max,['(gm_opt,Rneg_max)',newline,'(',num2str(1000*gm_opt,'%.2f'),'m,',num2str(Rneg_max,'%.0f'),')',newline,newline],'Interpreter','none');
    
83. text(gm_max,-Rm,['(gm_max,-Rm)',newline,'(',num2str(1000*gm_max,'%.2f'),'m,',num2str(-Rm,'%.0f'),')',newline,newline],'Interpreter','none');
    
84. legend('Negative Resistance','Max Negative Resistance','Motional Resistance','Location','Best');
    
85. 
    
86. 
    
87. syms Cc;
    
88. 
    
89. ww=wm*sqrt(1+Cm/Cc);
    
90. ff=ww/(2*pi);
    
91. 
    
92. Cc=-(w*imag(Zc))^-1;
    
93. Cc=double(subs(Cc,'gm',gm));
    
94. figure(20)
    
95. semilogx(gm,Cc,'b-');grid on
    
96. axis([0.1e-3,1000.0e-3,C3-1e-12 C3+Cload+1e-12]);
    
97. xlabel('gm(S)');
    
98. ylabel('Capacitance(F)');
    
99. title(['Capacitance VS. gm',newline,'fm=',num2str(fm/1000000,'%.f'),'MHz']);
    
100. hold on
     
101. 
     
102. xlim=get(gca,'Xlim');
     
103. plot(xlim,[max(Cc),max(Cc)],'c-');
     
104. plot(xlim,[min(Cc),min(Cc)],'m-');
     
105. 
     
106. ylim=get(gca,'Ylim');
     
107. plot([gm_crit,gm_crit],ylim,'k--');
     
108. plot([gm_opt,gm_opt],ylim,'k--');
     
109. plot([gm_max,gm_max],ylim,'k--');
     
110. 
     
111. clear xlim ylim;
     
112. text(10e-5,max(Cc),[' Cload+C3:',newline,' ',num2str(1e12*(Cload+C3),'%.1f'),'p',newline,newline],'Interpreter','none');
     
113. text(10e-5,min(Cc),[' C3:',newline,' ',num2str(1e12*C3,'%.1f'),'p',newline,newline],'Interpreter','none');
     
114. text(gm_crit,min(ylim),[' gm_crit:',newline,' ',num2str(1e3*gm_crit,'%.2f'),'m',newline,newline],'Interpreter','none');
     
115. text(gm_opt,min(ylim),[' gm_opt:',newline,' ',num2str(1e3*gm_opt,'%.2f'),'m',newline,newline],'Interpreter','none');
     
116. text(gm_max,min(ylim),[' gm_max:',newline,' ',num2str(1e3*gm_max,'%.2f'),'m',newline,newline],'Interpreter','none');
     
117. legend('Cc','Cload+C3','C3','Location','Best')
     
118. 
     
119. 
     
120. 
     
121. 
     
122. %A=2*Rm*w*C3*(C1*C2+C2*C3+C1*C3)/C1/C2
     
123. 
     
124. %semilogx(gm,subs(imag(Zc),'gm',gm),'r-');grid on
     

复制代码

jzr1989

love1226 发表于 2020-12-17 09:29
能否分享一下你的code,xiexie !!

1. clear
   
2. clc
   
3. syms s V1 V2 Vin real;
   
4. fm=4.0e6;Cm=5.0e-15;Rm=4000.0;
   
5. %syms fm Cm Rm;
   
6. wm=2*pi*fm;
   
7. Lm=wm^-2/Cm;
   
8. %syms Lm;
   
9. C3=5.0e-12;C1=16.0e-12;C2=16.0e-12;
   
10. %syms C3 C1 C2;
    
11. %gm=34.66e-3;
    
12. %syms gm;
    
13. %gm=0.001720210255586;
    
14. %gm=0.020914461554307;
    
15. gm=0.254279789744414;
    
16. 
    
17. Cload=C1*C2/(C1+C2);
    
18. w=wm*sqrt(1+Cm/(C3+Cload));
    
19. f=w/(2*pi);
    
20. wa=wm*sqrt(1+Cm/C3);
    
21. fa=wa/(2*pi);
    
22. 
    
23. [V1,V2]=solve(-(V1-V2)/(1/(s*Cm)+s*Lm+Rm)+s*C3*(V2-V1)-s*C1*V1==0,(V1-V2)/(1/(s*Cm)+s*Lm+Rm)-gm*Vin-s*C2*V2-s*C3*(V2-V1)==0,[V1,V2]);
    
24. LoopGain=V1/Vin;
    
25. syms ww ff
    
26. LoopGain_jw=subs(LoopGain,'s',1i*ww);
    
27. LoopGain_jf=subs(LoopGain_jw,'ww',2*pi*ff);
    
28. LoopGain_real=real(LoopGain_jf);
    
29. LoopGain_imag=imag(LoopGain_jf);
    
30. LoopGain_mag=sqrt((LoopGain_real)^2+(LoopGain_imag)^2);
    
31. LoopGain_mag_db=20*log10(sqrt((LoopGain_real)^2+(LoopGain_imag)^2));
    
32. 
    
33. LoopGain_pha=atan(LoopGain_imag/LoopGain_real)*180/pi;
    
34. 
    
35. %ff=1:1e6:100e6;
    
36. ff=fm-20e3:0.05e3:fm+40e3;
    
37. LoopGain_mag_db=subs(LoopGain_mag_db,'ff',ff);
    
38. LoopGain_pha=subs(LoopGain_pha,'ff',ff);
    
39. 
    
40. figure(1)
    
41. hold on
    
42. 
    
43. subplot(2,1,1)
    
44. plot(ff,LoopGain_mag_db,'b')
    
45. xlabel('Frequency(Hz)');
    
46. ylabel('Magnitude(dB)');
    
47. grid on
    
48. hold on
    
49. ylim=get(gca,'Ylim');
    
50. plot([f,f],ylim,'k--');
    
51. plot([fm,fm],ylim,'k--');
    
52. plot([fa,fa],ylim,'k--');
    
53. clear xlim ylim;
    
54. 
    
55. subplot(2,1,2)
    
56. plot(ff,LoopGain_pha,'b')
    
57. xlabel('Frequency(Hz)');
    
58. ylabel('Phase(deg)');
    
59. grid on
    
60. hold on
    
61. ylim=get(gca,'Ylim');
    
62. plot([f,f],ylim,'k--');
    
63. plot([fm,fm],ylim,'k--');
    
64. plot([fa,fa],ylim,'k--');
    
65. clear xlim ylim;
    
66. 
    
67. suptitle(['Oscillaor Loop Gain',newline,'fm=',num2str(fm/1e6,'%.f'),'MHz']);
    
68. hold on
    
69. 
    
70. % [LoopGain_num,LoopGain_den]=numden(LoopGain);
    
71. %
    
72. % LoopGain_num_coeffs=double(coeffs(expand(LoopGain_num),s,'All'));
    
73. % %  fliplr(LoopGain_num_coeffs);
    
74. %
    
75. % LoopGain_den_coeffs=double(coeffs(expand(LoopGain_den),s,'All'));
    
76. % %  fliplr(LoopGain_den_coeffs);
    
77. %
    
78. % LoopGain_tf=tf(LoopGain_num_coeffs,LoopGain_den_coeffs);
    
79. %
    
80. % figure(2)
    
81. %
    
82. % P=bodeoptions;
    
83. % P.Grid='on';
    
84. % P.FreqScale='log';
    
85. % %P.Xlim={[fm-2e6 fm+2e6]};
    
86. % %P.XlimMode={'manual'};
    
87. % P.FreqUnits='Hz';
    
88. % bodeplot(LoopGain_tf,P,'r')
    
89. % % bode(LoopGain_tf)
    
90. % hold on
    
91. 
    
92. ylim=get(gca,'Ylim');
    
93. plot([f,f],ylim,'k--');
    
94. plot([fm,fm],ylim,'k--');
    
95. clear xlim ylim;
    

复制代码

l13787908861

路过学习，很实用，学习分享。

l13787908861

路过学习，很实用，学习分享。

l13787908861

路过学习，很实用，学习分享。