[讨论] 请问怎么消除LDO中的共轭极点

linda_xia 2010-5-19 12:26 楼主

在对LDO做开环频率特性仿真时发现出现了很多共轭极零点对，严重影响了环路稳定性。比如下面这样的请问这些共轭的极零点是怎么产生的，该如何消除呢
poles (rad/sec)                poles ( hertz)
**********************************************************************
real          imag          real          imag
0.             0.             0.             0.
-647.5153k       0.          -103.0553k       0.
2.4266x       2.1366g    386.2091k    340.0456x
2.4266x       -2.1366g    386.2091k    -340.0456x
-6.2383x       41.8075x    -992.8555k       6.6539x
-6.2383x    -41.8075x    -992.8555k       -6.6539x
-8.3755x       0.          -1.3330x       0.
-125.3032x       0.          -19.9426x       0.
-157.9078x    130.3308x    -25.1318x       20.7428x
-157.9078x    -130.3308x    -25.1318x    -20.7428x
-160.2610x       0.          -25.5063x       0.
-554.6786x       0.          -88.2798x       0.
-790.4263x       0.          -125.8003x       0.
-954.1746x       0.          -151.8616x       0.
-1.0282g       0.          -163.6487x       0.
-1.7103g       0.          -272.2043x       0.
-1.8999g       0.          -302.3841x       0.
-2.7443g       0.          -436.7655x       0.
-3.0859g       0.          -491.1404x       0.
-3.2674g       0.          -520.0183x       0.
-3.9267g       0.          -624.9493x       0.
-5.2728g       0.          -839.1947x       0.
-6.1747g       3.0310g    -982.7408x    482.3919x
-6.1747g       -3.0310g    -982.7408x    -482.3919x
-6.4418g       0.          -1.0252g       0.
-6.5997g       -1.3448g       -1.0504g    -214.0311x
-6.5997g       1.3448g       -1.0504g    214.0311x
  -12.1895g       0.          -1.9400g       0.
  -14.6858g       0.          -2.3373g       0.
  -29.8962g       0.          -4.7581g       0.
  -67.3424g       0.          -10.7179g       0.
-279.7558g       0.          -44.5245g       0.
-289.3704g       0.          -46.0547g       0.
   zeros (rad/sec)                zeros ( hertz)
**********************************************************************
real          imag          real          imag
0.             0.             0.             0.
-801.4735k       2.1265g    -127.5585k    338.4503x
-801.4735k       -2.1265g    -127.5585k    -338.4503x
-8.3734x       0.          -1.3327x       0.
-125.3032x       0.          -19.9426x       0.
-157.9101x    -130.3171x    -25.1322x    -20.7406x
-157.9101x    130.3171x    -25.1322x       20.7406x
-166.0539x       0.          -26.4283x       0.
-573.6539x       0.          -91.2999x       0.
-578.5310x       1.2014g    -92.0761x    191.2025x
-578.5310x       -1.2014g    -92.0761x    -191.2025x
-791.0936x       0.          -125.9065x       0.
-954.1687x       0.          -151.8607x       0.
-1.7109g       0.          -272.3010x       0.
-1.8997g       0.          -302.3440x       0.
-3.2674g       0.          -520.0190x       0.
-3.4121g       0.          -543.0456x       0.
-3.9342g       0.          -626.1398x       0.
-5.3604g       -3.7810g    -853.1397x    -601.7602x
-5.3604g       3.7810g    -853.1397x    601.7602x
-6.3187g       -2.4546g       -1.0056g    -390.6544x
-6.3187g       2.4546g       -1.0056g    390.6544x
-6.4422g       0.          -1.0253g       0.
-6.7558g       0.          -1.0752g       0.
9.0165g       0.             1.4350g       0.
  -12.1895g       0.          -1.9400g       0.
  -14.6897g       0.          -2.3379g       0.
  -29.8960g       0.          -4.7581g       0.
31.9809g       0.             5.0899g       0.
  -67.3409g       0.          -10.7176g       0.
  202.1280g       0.          32.1697g       0.
-279.7529g       0.          -44.5241g       0.
-289.3704g       0.          -46.0547g       0.