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university:courses:electronics:electronics-lab-6m [04 Mar 2019 12:47]
Antoniu Miclaus [Procedure:]
university:courses:electronics:electronics-lab-6m [23 Aug 2019 12:51]
Antoniu Miclaus
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-====== Activity ​6M. NMOS as a Current Mirror ======+====== ActivityNMOS as a Current Mirror ======
  
 ===== Objective: ===== ===== Objective: =====
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 ===== Hardware Setup: ===== ===== Hardware Setup: =====
  
-In the current mirror configuration,​ the opamp serves as a virtual ground at the mirror input (gate) node to convert the voltage steps from AWG 1 ( W1 output ) into current steps through the 1K? resistor. The drain voltage is swept using a ramp from AWG 2(output ​W2) set to 3V peak to peak with the offset to 1.5V. V<​sub>​DS</​sub>​ of output device M<​sub>​2</​sub>​ is measured differentially by scope inputs 1+, 1-. The mirror output current is measured by scope inputs 2+. 2- across 1K? resistor, R<​sub>​2</​sub>​.+In the current mirror configuration,​ the opamp serves as a virtual ground at the mirror input (gate) node to convert the voltage steps from AWG 1 ( W1 output ) into current steps through the 1K? resistor. The drain voltage is swept using a ramp from AWG 1(output ​W1). Load the stairstep.csv file, set amplitude ​to 3V peak-to-peak with the offset to 1.5V. 
 +V<​sub>​DS</​sub>​ of output device M<​sub>​2</​sub>​ is measured differentially by scope inputs 1+, 1-. The mirror output current is measured by scope inputs 2+. 2- across 1K? resistor, R<​sub>​2</​sub>​.
 If you don't want to use the op-amp configuration the following simplified configuration can be used as well.  If you don't want to use the op-amp configuration the following simplified configuration can be used as well. 
  
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 Two identical transistors with the same gate to source voltage will have the same drain current I<​sub>​D</​sub>​. The second transistor, M<​sub>​2</​sub>,​ in effect mirrors the current in the first, M<​sub>​1</​sub>​. Remembering the drain current to gate source voltage relationship for a MOS transistor: Two identical transistors with the same gate to source voltage will have the same drain current I<​sub>​D</​sub>​. The second transistor, M<​sub>​2</​sub>,​ in effect mirrors the current in the first, M<​sub>​1</​sub>​. Remembering the drain current to gate source voltage relationship for a MOS transistor:
  
-{{ :​university:​courses:​electronics:​a6m_ne1.png?​250 |}}+{{ :​university:​courses:​electronics:​a6m_ne1.png?​ 250 |}}
  
 where K =μ<​sub>​n</​sub>​C<​sub>​ox</​sub>/​2<​sub></​sub>​ and λ can be taken as process technology constants.\\ where K =μ<​sub>​n</​sub>​C<​sub>​ox</​sub>/​2<​sub></​sub>​ and λ can be taken as process technology constants.\\
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 <WRAP centeralign>​ Figure 5 Current Mirror waveform </​WRAP>​ <WRAP centeralign>​ Figure 5 Current Mirror waveform </​WRAP>​
  
 +<WRAP round download>​
 **Resources:​** **Resources:​**
   * Fritzing files: [[ https://​minhaskamal.github.io/​DownGit/#/​home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​fritzing/​mos_current_mirror_bb | mos_current_mirror_bb]]   * Fritzing files: [[ https://​minhaskamal.github.io/​DownGit/#/​home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​fritzing/​mos_current_mirror_bb | mos_current_mirror_bb]]
   * LTspice files: [[ https://​minhaskamal.github.io/​DownGit/#/​home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​ltspice/​nmos_cur_mirror_ltspice | mos_current_mirror_ltspice]]   * LTspice files: [[ https://​minhaskamal.github.io/​DownGit/#/​home?​url=https://​github.com/​analogdevicesinc/​education_tools/​tree/​master/​m2k/​ltspice/​nmos_cur_mirror_ltspice | mos_current_mirror_ltspice]]
 +</​WRAP>​
 ===== Questions: ===== ===== Questions: =====
  
university/courses/electronics/electronics-lab-6m.txt · Last modified: 25 Jun 2020 22:07 (external edit)