Cadence OrCAD PCB Designer
Cadence OrCAD PCB Designer Cadence OrCAD PCB Designer
Figure 3. Gain as a function of frequency for different bypass capacitors. Hint for demonstrators. My results are in figure 3. Increasing the bypass capacitor improves the gain until it is limited at low frequency by C 1 instead. There isn’t much difference between the results for 100 µF and 1000 µF so I would use 100 µF. ❦ 4 Preparation for PCB layout Once the design of the circuit has been finalised, it should be laid out on the printed circuit board (PCB). This takes a few steps before you leave Capture. The overall design flow for making a PCB is shown in figure 4 on the next page and there is a summary in section 9. 4.1 Edit the circuit First, the ‘virtual components’ in the schematic must be replaced by real components. Here this means the voltage sources and param block. There is no way that you can build a real circuit with a param block for instance! (Well, you could use a pair of sockets and unplug the component to change it.) The real circuit has connectors for input, output and power, which must be placed instead. This is shown in figure 5. The types of connector are HEADER 2 and the like. They are in the connector library, which is in the directory one level above pspice. The connectors are oriented so that pin 1 is connected to ground in both cases. It is shown by a square marker on the PCB. I have changed the names to make them more descriptive than the defaults, such as HEADER 2; do not edit the references J1 and J2. Add text to label the pins of each connector and put your name on the circuit, or you won’t be able to identify it when it comes out of the printer. Hint for demonstrators. Some students change the Reference (J1 or J2) of the connectors to Input or Output instead of changing the Value (HEADER 2 or HEADER 3). This causes trouble with the netlister later on. ❦ 10
Capture Draw schematic PCB Editor Set up bare board (outline, design rules) Add footprints Create netlist Engineering Change Order (ECO) Libraries Place and arrange components Export to SPECCTRA Route board manually Route board automatically Check vias, gloss board Route board automatically Spread and mitre tracks Annotate and print board Return to PCB Editor Figure 4. Design flow for making a PCB with Capture and PCB Editor. The three paths for PCB Editor depend on whether the tracks are drawn manually (as we shall do for our first design), automatically within PCB Editor, or by running the automatic router (SPECCTRA) as a separate application. Input Gnd J1 2 1 C1 1u R1 7.4k Q1 R3 390 BFY51 3 2 1 J2 Output +10V Output Gnd Input R2 2.7k R4 180 C2 100u 16V Figure 5. The simple, one-transistor amplifier with only real components, ready for layout. 11
- Page 1 and 2: Electronic Design Project 2 Cadence
- Page 3 and 4: The first two should be familiar fr
- Page 5 and 6: 2. The base-emitter junction of a t
- Page 7 and 8: • Select an Analog or Mixed A/D p
- Page 9: Figure 2. Gain as a function of fre
- Page 13 and 14: 2. Choose Edit > Properties. . . fr
- Page 15 and 16: Figure 6. Completed dialogue box fo
- Page 17 and 18: Figure 7. Completed dialogue box fo
- Page 19 and 20: Figure 8. Screenshot of OrCAD PCB E
- Page 21 and 22: Figure 9. The Placement dialogue bo
- Page 23 and 24: • To rotate a selected component,
- Page 25 and 26: Hint for demonstrators. Some studen
- Page 27 and 28: • Usually the Plot scaling should
- Page 29 and 30: Table 2. Footprints for instrumenta
- Page 31 and 32: Figure 13. Constraint manager after
- Page 33 and 34: Figure 15. Screenshot of SPECCTRA,
- Page 35 and 36: Figure 17. My one-sided layout afte
- Page 37 and 38: Figure 18. Printout at actual size
- Page 39 and 40: • The pins of the integrated circ
- Page 41 and 42: in 2007-08, which was an electronic
- Page 43 and 44: Property Editor with Edit > Propert
- Page 45 and 46: 9 Summary: PCB design flow This lis
- Page 47 and 48: A Where to learn more The online he
- Page 49 and 50: B Power-user tips and random jottin
- Page 51 and 52: Figure 24. Padstack editor settings
- Page 53 and 54: Figure 26. Screenshot and photomask
- Page 55 and 56: 3. The list on the right-hand side
- Page 57 and 58: • Our local allegro library doesn
Capture<br />
Draw<br />
schematic<br />
<strong>PCB</strong> Editor<br />
Set up bare board<br />
(outline, design rules)<br />
Add<br />
footprints<br />
Create<br />
netlist<br />
Engineering<br />
Change Order<br />
(ECO)<br />
Libraries<br />
Place and arrange<br />
components<br />
Export to<br />
SPECCTRA<br />
Route board<br />
manually<br />
Route board<br />
automatically<br />
Check vias,<br />
gloss board<br />
Route board<br />
automatically<br />
Spread and<br />
mitre tracks<br />
Annotate and print<br />
board<br />
Return to<br />
<strong>PCB</strong> Editor<br />
Figure 4. Design flow for making a <strong>PCB</strong> with Capture and <strong>PCB</strong> Editor. The three paths for<br />
<strong>PCB</strong> Editor depend on whether the tracks are drawn manually (as we shall do for our first<br />
design), automatically within <strong>PCB</strong> Editor, or by running the automatic router (SPECCTRA) as<br />
a separate application.<br />
Input<br />
Gnd<br />
J1<br />
2<br />
1<br />
C1<br />
1u<br />
R1<br />
7.4k<br />
Q1<br />
R3<br />
390<br />
BFY51<br />
3<br />
2<br />
1<br />
J2<br />
Output<br />
+10V<br />
Output<br />
Gnd<br />
Input<br />
R2<br />
2.7k<br />
R4<br />
180<br />
C2<br />
100u<br />
16V<br />
Figure 5. The simple, one-transistor amplifier with only real components, ready for layout.<br />
11
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